SFqio 
 UN35 
 
ilNIA PUB[JCATIONS 
 
 BULLETIN 
 
 PHILOSOPHICAL SOCIETY 
 
 Scientific Series. Vol. I, No. 19, pp. 3 7«-t8«, March, 1914 
 
 Loco^veed Disease of Sheep 
 
 BY 
 
 HARRY T. MARSHALL 
 
 UNIVERSITY OF VIRGINIA 
 ChaplottesTiUe, Virgiuia, U. S. A. 
 
 •fraptr 
 
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 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 BULLETIN OF THE PHILOSOPHICAL SOCIETY 
 
 SCIENTIFIC SECTION 
 
 Vol. I, No. 19, pp. 373-436 March, 1914 
 
 LOCOWEED DISEASE OF SHEEP* 
 
 BY 
 
 HARRY T. MARSHALL. 
 
 (Published by permission of the Secretary of Agriculture.) 
 
 Synomjms: Loco disease, loco, locoism, crazyweed disease, crazy dis- 
 ease, rattleweed disease. 
 
 There is an opinion wadely current that the live stock ranging over the 
 Western plains and Rocky Mountain regions are remarkably free from 
 disease. The general prosperity of the ranch owners has served in great 
 measure to divert attention from the losses and failures befalling certain of 
 their number and it has taken many years to bring a reahzation of the 
 menace presented by diseases to the continued success of stock raisers in the 
 West. That parasitic diseases occur in sections of the West has been 
 showTi by Curtice, Stiles, Ransom, and other members of the Bureau of 
 Animal Industry. Recently Hallf has shown by charts the present 
 
 * The work described in the following report was conducted by me at the request 
 of the U. S. Department of Agriculture, under the supervision of Prof. V. K. Chesnut 
 of the Office of Poisonous Plant Investigation. In addition to his hearty cooperation 
 in many other waj'^s Prof. Chesnut identified the locoweeds used in the experiment 
 and selected the regions over which the loco feeding experiments were conducted. 
 Dr. Charles Wardell Stiles was kind enough to determine the specific identity of the 
 parasites found in my examinations of the sheep during 1903. Mr. B. H. Ransom of the 
 the Bureau of Animal Industry has made a special study describing a new stomach 
 worm of sheep found in the course of my autopsies (Bureau of Animal Industry, 1911, 
 Bull. 127, pp. 62-66). The authorities of the Montana Agricultural College cooperated 
 very courteously with us and moreover performed a valuable and important work in 
 studying the market value of the sheep which were left over from my experiments. 
 Finally, it is a pleasure to acknowledge, even at this late date, my appreciation of 
 the hospitality, interest and assistance everywhere offered us by the ranchmen of 
 Montana. 
 
 tU. S. Bureau of Animal Industry, 27th Report for 1910; pub. 1912, pp. 419-461. 
 
 373 
 
374 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 known distribution of the parasitic diseases of sheep, but complete sys- 
 tematic studies of the prevaiUng parasitic diseases of Western Hve stock 
 hav^e not been made and knowledge upon this subject is incomplete. With 
 regard to poisonous plants it has been shown in a number of publications 
 from the Bureau of Plant Industry such as those by V. K. Chesnut and 
 by Chesnut and Wilcox that there are several widespread and highly 
 poisonous plants on the Western plains which occasionally cause great 
 losses among stock. 
 
 The ranchmen themselves attribute great losses to the poisonous ac- 
 tion of the locoweed, and this matter has given rise to much writing. The 
 botanical characteristics and distril)ution of the various locoweeds were 
 studied by Chesnut and others. After Chesnut 's report appeared — in 
 which he also described the general symptoms of the locoed animals— I 
 was engaged by the Bureau of Plant Industry to study locoed animals in 
 Montana for the purpose first, of giving a clear description of the s^Tnptoms 
 characteristic of locoweed poisoning, and second, of locating and describ- 
 ing the anatomical changes produced in animals from eating the weed. As 
 the result of my fincUngs it proved necessary to conduct a feeding experi- 
 ment in order to settle the vexed question as to whether it is possible to 
 obtain uncomplicated cases of genuine locoweed poisoning. Inasmuch as 
 other publications have appeared upon the subject of locoweed poisoning 
 since 1903 and 1904, when my studies were made, I conclude this report with 
 a review of the recent literature and ^^^th a discussion of the loco problem, 
 as it confronts us today. 
 
 The report falls into several divisions : 
 
 A. Information obtained from the ranclmien and from literature. 
 
 B. The results of examinations of tjq^ical "locoed" sheep as they 
 were met with on the ranches. 
 
 C. The description of feeding experiments and the results obtained 
 from them. 
 
 D. Discussion of the parasitic diseases encountered. 
 
 E. A review of recent publications dealing with loco disease. 
 
 F. The present status of the "Loco problem." 
 
LOCOWEED DISEASE OF SHEEP 375 
 
 A. INFORMATION OBTAINED FROM THE RANCHMEN AND FROM THE 
 LITERATURE. 
 
 The spread of loco disease. Inasmuch as Marsh* and Crawfordf have 
 pubhshed elaborate bibhographies and historical reviews of locoweed 
 disease, only special features will be selected for remark here. It seems 
 probable from such information as can be obtained that loco disease 
 was first observed in Mexico or Texas, and thus received its Spanish 
 name of "loco" or "crazy" disease. It was known in the seventies in 
 Cahfornia; about the same time in Texas and Colorado; a few years later in 
 Wyoming, and apparently it was first observed in Montana about 1884, 
 when Jacob Severence described "loose-teeth lamljs." Its general recog- 
 nition in Montana dates from about 1890. It seems probable that loco 
 disease spread northward from Mexico, the disease becoming notable 
 in each locality ten, twelve, or fifteen years after the ranges were first 
 occupied by live stock. Apparently a very large part of the live stock of 
 the West is descended from old Mexican stock, the animals having been 
 driven further and further north as fresh ranges were needed. 
 
 Definition. The general opinion in the West is that locoweed disease 
 is a dehnite form' of drug poisoning produced by the locoweed in animals 
 which have formed the habit of eating the weed. Most ranchmen believe 
 that the whole plant is poisonous, a few hold that the poison resides in the 
 flowers, a large number consider the roots to be the most dangerous part 
 of the plant. Some l)elieve that one variety of locoweed is more dangerous, 
 others, another. 
 
 A small number of ranchmen reject the view that the locoweed is poison- 
 ous. Most of these men believe that the cra^dng for the locoweed prevents 
 animals from eating a sufficient quantity of nutritious food, and that the 
 symptoms are those of starvation. Others contend that the locoweed is 
 of itself altogether harmless, and that the symptoms are caused by some 
 worm or other parasite residing in the locoweed. A ver3^ small number 
 believe that all cases of "locoweed disease" are in reality examples of 
 other diseases, such as starvation, or parasitic infection. 
 
 The locoweed. There' is some confusion as to the identity of the loco- 
 weed. Many other plants have been called locoweed, and there is no 
 doubt that many cases of poisoning by other plants have been looked 
 upon as cases of locoweed disease. The botanical characteristics of the 
 various locoweeds have been given in Bulletins 20 and 26 of the Depart- 
 
 * Bureau of Animal Industry, Bull. 112, 1909. 
 t Bureau Plant Indastrv, Bull. 129, 1908. 
 
376 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 ment of Agriculture, and in ''Preliminary Catalogue of Plants Poisonous 
 to Stock," Annual Report B. A. I. for 1898 and 1899, and by Marsh (loc. 
 cit.). 
 
 The plants most closely connected with the disease are members of 
 the pea or bean family (Fabaceae or more broadly, Leguminosae) . The 
 most widely distributed locoweeds are the Astragallus mollissimus, or 
 "woolly locoweed" or "purple locoweed," the Aragallus spicatus (Hook) 
 Rydberg, or "white locoweed," and the Aragallus lamberti. According to 
 Marsh, who quotes Prof. C. F. Wheeler, Aragallus spicatus is identical with 
 Aragallus lamberti, but Rydberg separates them as distinct. The Aragallus 
 spicatus is the locoweed most abundant in Montana. These locoweeds are 
 found either alone or together, over much of the area in which the disease 
 is reported. Several other closely related plants are also called locoweed. 
 Experiments with the locoweed and its extracts have yielded such in- 
 constant results that they cannot be relied upon. The more recent works 
 of Crawford, Alsberg and Marsh wdll be discussed later. 
 
 Etiology. While the locoweed is generally regarded as the direct cause 
 of the disease there are many factors which are supposed to play a minor 
 part in the development of locoism. Special efforts were made to obtain 
 full information from the ranchmen as to accessory and predisposing fac- 
 tors. The following is a summary of the information obtained in this way 
 from the ranchmen. 
 
 1. Species. Horses and sheep are most often the victims, cattle are 
 affected but rarely, especially in Montana (1903-1904). The Angora 
 goats of Montana are said to be quite susceptible. It is questionable 
 Avhether any other animals (deer, elk, etc.) ever contract the disease. 
 
 2. Age. The statement can be obtained from most ranchmen in Mon- 
 tana that adult animals very rarely if ever acquire the disease. The symp- 
 toms first appear during the first year of life or more commonly during the 
 second year. In the uncommon cases in which the s^inptoms first appear in 
 an adult it is assumed that the disease existed but was latent when the 
 animal was younger. 
 
 3. Se.r. Males and females are equally afi'ected. 
 
 4- Food. If animals receive a sufficient supply of nutritious food 
 (grass, alfalfa, etc.), they will rarely if ever fall victims to the "loco habit." 
 The great majority of all ranchmen interviewed united in affirming the 
 close relationship between locoweed disease and an insufficient food supply. 
 An unusually dry season, overstocking of the ranches, or allowing too 
 short a time for a grazed section to recover may reduce the available supply 
 of nutritious grasses, result in partial starvation of the animals and turn 
 them to the locoweed to satisfv their hunger. 
 
LOCOWEED DISEASE OF SHEEP 377 
 
 o. Water. A number of ranchmen hold that there is just as close a re- 
 lationship between an insufficient water supply and locoweed disease, as an 
 insufficient food supply. 
 
 6. Salt. It has been stated that where animals are regularly and abun- 
 dantly salted they are much less prone to become "locoed." The alkali 
 eaten by unsalted animals does not serve as a suitable substitute for salt. 
 Many ranchmen maintain that locoweed disease can be completely averted 
 if attention is paid to this matter. 
 
 7. Lowered vitality. There is no one point upon which the ran(;hmen 
 are more thoroughly agreed than in the assertion that healthy animals 
 never acquire the locoweed disease. Only one or two ranchmen claim that 
 healthy, fat stock can become locoed. In practically every case the gen- 
 eral health of an animal must be lowered before it will form the "loco 
 habit." It is even stated by some that a healthy animal may eat a little 
 of the locoweed along with its regular food, and not form the "loco habit" 
 nor show any bad effects. This, however, is denied by most ranchmen. 
 The general health may be lowered as the result of insufficient food, salt, 
 or water, or as the result of other causes, such as exposure to inclement 
 weather, lack of care on the part of the shepherd, a frail constitution, or 
 any previous disease. 
 
 8. Geographical distribution. From information received by the Poison- 
 ous Plant Investigation it seems that the disease is found wherever the 
 weed occurs, and nowhere else. The answer to circular letters indicate 
 that at present (1904) locoweed disease prevails from Texas to Montana, 
 and from Western Kansas to California. The weed and the disease are 
 both common at an elevation of from 4000 feet to 7000 feet or even 8000 
 feet above the sea. In Montana the regions most affected appear to be the 
 foot hills and high plateaus around Judith Basin, the Musselshell and the 
 Yellowstone Rivers. In central Montana horses are more affected, in 
 Southern Montana sheep. 
 
 9. Soil. The locoweed is very hardy and thrives even where the nutri- 
 tious grasses cannot grow well. A hght soil or a broken rocky soil is favorable 
 for the weed. The attempt to prove a direct connection between an alka- 
 line soil and the locoweed disease has not succeeded, even in the cases re- 
 ported by Crawford. 
 
 10. Incidence. It is impossible to estimate the numerical loss attributed 
 to locoweed disease. In Montana and Colorado there is probably an aver- 
 age loss of from 10 to 25 per cent of the annual increase from this source. 
 The loss is from sickness and depreciation in value as much as from death 
 of the animals. Individual ranchmen have been met with who have been 
 
378 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 forced out of Ixisiness by this scourge, while other ranchmen in the same 
 neighborhood have escaped loss from the disease almost altogether. Ac- 
 counts indicated in 1903 that the disease was increasing. According to 
 the ranchmen there are the most remarkable variations in the prevalence 
 of the disease from year to year. A region previously free from the disease 
 may suddenly be devastated by it, only to have it subside or disappear 
 again after a year or two. It could not be ascertained that such outbreaks 
 are coincident with a sudden spread of the locoweed. It is claimed by 
 some, however, that the abundance of the weed varies from year to year. 
 
 11. Old ra7iges. The " loco disease " does not make its appearance when 
 a ranch is first occupied. Thus in Montana the disease was first noticed 
 about ten or twelve years after the plains were settled by the rangers. 
 In Eastern Colorado the evidence was similar. The stock rangers explain the 
 delayed appearance of the disease as the result of a steady decrease of avail- 
 able grazing lands, combined with a rapidly increasing overstocking of 
 the ranches, producing a shortage of grass, and the adoption of the locoweed 
 as food by the hungry animals.* 
 
 IS. Outbreaks. It is rare for isolated cases to occur, although they are 
 met with. Such cases are most often found in horses. As a rule if one 
 animal on the ranch becomes "locoed" a large proportion of all the young 
 animals will develop the disease. As stated above locoweed disease is 
 frequently enzootic throughout an entire region. Whether the infection 
 attacks all animals or only single species could not be determined. The 
 evidence at hand indicates that the "loco" outbreak is confined to one 
 species, for example, sheep. 
 
 18. Seaso7ial variations. In Montana the first cases of "loco" occur a 
 few weeks after the plant becomes green — that is during April and May. 
 These are regarded as chiefly relapses from the year before. Very few 
 cases develop during the summer. The greatest number of new cases ap- 
 pear in the autumn — November and December. Further south (Colorado) 
 the height of the disease is said to be earher in the spring and later in the 
 autumn. 
 
 The ranchmen hold divergent views as to the relation between the in- 
 cidence of the disease and the season's rainfall, some holding that more 
 
 * Within recent years the number of animals grazed on a given tract of land has 
 risen enormously. One ranger in Montana informed me that 40,000 sheep now graze 
 on a tract formerly ranged over by 6000. The fencing in of the ranges, and the settle- 
 ment of the public lands, have served to curtail the available ranging lands to a frac- 
 tion of their former extent, so that at the present time a larger number of animals 
 grazes over a smaller tract than formerly, and returns to the same tract at shorter 
 intervals. 
 
LOCOWEED DISEASE OF SHEEP 379 
 
 "loco disease" is seen during moist seasons, others that a dry season favors 
 the spread of the disease by decreasing the amount of the nutritious grasses. 
 
 Symptoms arid course of the disease. The onset is described as being 
 usually gradual and insidious, several weeks after the animal first eats 
 the weed. A rapid onset is described at times, and occasionally symptoms 
 appear within a week after exposure. In Eastern Colorado it seems not un- 
 usual for a horse to become "locoed" a day or two after beginning to eat 
 the weed. The symptoms are more definite in the horse. A previously well 
 broken horse becomes unmanageable, bucking, rearing and exhibiting vari- 
 ous vicious traits, together with a high degree of nervousness. The animal 
 appears to suffer from defective vision and even from hallucinations. It 
 is subject to tremors of excitement. Most characteristic appears to be 
 the tendency of "locoed" horses to balk at objects in front of them. Thus 
 they will balk at a stick or a rope lying in their path, and if forced to cross 
 it, they will clear it with a leap several feet in the air. It is said that a " lo- 
 coed" horse cannot be led nor ridden, though it may at times be driven, 
 but that when once started the horse will not stop before it is exhausted. 
 The nervous symptoms continue. Very soon the animal begins to lose 
 strength and weight; emaciation finally becomes extreme, the coat is 
 rough and dull, the ears and head droop, the gait becomes weak and un- 
 steady, the ej^es sunken and glassy, and the animal very apathetic. Oc- 
 casionall}^ one side or one limb may be weaker than the rest of the animal. 
 Stiffness of the hind legs is especially common. Schwartzkopf states that 
 the pupils are widely dilated and that there is a decrease of sensibility to 
 mechanical stimulation. Apparently the animal is in almost a constant 
 state of nervous tremor. The disease is usually chronic, lasting from several 
 months up to two or three years. The horse spends its time searching for the 
 locoweed, which it may even dig up by the roots with its hoof. In the last 
 stages the horse may walk bhndly into a tree or rock and stand pushing 
 against it until it drops from exhaustion, or it may fall in the water from 
 which it is drinking and drown. In the chronic disease, horses occasionally 
 exhibit acute maniacal attacks from which they may die suddenly with 
 evidences of great pain. Acute attaclss, can be brought on by exciting the 
 animal or by making it exercise until it is hot. 
 
 Locoweed disease of sheep and cattle is less fully described. The chief 
 symptoms are the habit of eating the locoweed, nervousness, loss of weight 
 and strength ending in great emaciation, with dull glassy eyes, rough coat, 
 and finally death from exhaustion. Stiffness of the muscles of the neck and 
 hind legs is regarded as quite characteristic in sheep. 
 
 Morbid anatomy. No characteristic lesion has been found except the 
 
380 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 changes described by Marsh (I. c.) and reviewed below in Section E. An 
 increase in the fluid beneath the meninges and in the ventricles of the brain 
 has been described by Stalker and by Schwartzkopf. Scheuchardt states 
 that Schwartzkopf found no bacteria in his cases. 
 
 Prognosis. The outlook for locoed animals is usually bad. If the 
 disease is detected in the early stage the animal may be saved if it is fed 
 up on grain, hay, etc., or if sent to a country free from the weed. As a rule 
 the disease is not detected early, and the general attitude of the ranchman 
 is that of non-interference. Even after an apparent cure the animal will 
 relapse if turned out to graze in the former pasturage. 
 
 B. EXAMINATIONS OF " LOCOED" SHEEP. 
 
 Several hundred "locoed" sheep were seen on various ranches in Mon- 
 tana. No locoed horses could be found. Loco disease of cattle is a rarity 
 in Montana and no cases could be found. Experienced sheep raisers selected 
 a few of the illest and most typically locoed sheep from among the invalids 
 and turned them over to me. Animals selected in this way furnished the 
 materials for the following stud3^ 
 
 Six of the illest lambs obtainable were fed for about two weeks on loco- 
 weed (A. spicatus), gathered fresh every day. The animals did not like the 
 food, and at first ate sparingly of it, but more abundantly after a few days. 
 No change in their condition could be detected as the result of this diet, and 
 no acute symptoms were induced (see cases 8, 9 and 1 1) . 
 
 A synopsis of the cases examined follows. The anatomical diagnosis 
 was usually confirmed by the microscopic study of tissues fixed in Zenker's 
 fluid or alcohol, sectioned and stained with hematoxylin and eosin. The 
 central nervous system was not studied microscopically, but the brain, 
 cord and membranes were examined at autopsy. 
 
 Histories of sheep studied during September and October of 1903. 
 
 Ammal No. 1. Sheep, female, about eighteen months old from the Briggs-Ellis 
 Ranch, Big Timber, Montana (Mr. James Vestal), September 24. This sheep was 
 picked out by Mr. Vestal from an invalid band of between fifteen and thirty "locoed" 
 animals, and selected by. him as presenting the features of loco most typically and 
 most severely. 
 
 When examined, animal was in corral, separated from other sheep; appeared 
 apathetic, not eating nor noticing its surroundings. When alarmed, it ran off at a 
 trot with a stiff gait and stumbling, the legs flying out in an incoordinate manner. 
 The sheep was very weak and tremulous, especially in the hind legs, the tremor worse 
 on movement. There was slight lateral nystagmus. When laid on the ground the 
 animal was hardly able to rise. The hind legs were not able properly to support the 
 
LOCOWEED DISEASE OF SHEEP 381 
 
 animal. The pupils were only moderately dilated. The animal was greatly emaciated 
 and undersized, and stood with head and ears drooping, hardly making a movement. 
 Observed to remain in one position for one hour and thirty minutes and then moved 
 only upon being disturbed. Every two or three minutes a brief spasm contracted the 
 abdominal muscles, less often the muscles of one of the legs. 
 
 The vision of the animal was apparently good. She observed movements 10 or 20 
 feet away. When the hand was waved around slowly at a distance of 2 feet from 
 the animal, she became greatly alarmed and trembled, and shrank against the wall. 
 Hearing apparently acute. If hands were clapped together, even gently, up to a dis- 
 tance of 20 feet from the animal it quivered at the clap but paid no further attention. 
 Tactile sensation apparently not exaggerated. The end of the nose and skin of the 
 bodj' were not unduly sensitive. 
 
 September 26 at 12.30 p.m. animal chloroformed. Autopsy No. 1 performed at 
 once. Upon opening the spinal cord and brain, firm adhesiops were found between 
 the dura and the base of the skull along the right side extending from the level of the 
 sella turcica posteriorly nearly to the foramen magnum. Upon removing the dura 
 an abscess was opened into between the dura and the base of the skull containing be- 
 tween 2 and 4 drams of thick, viscid, yellow pus with a faint, unpleasant, rather fishy 
 odor. 
 
 The brain was symmetrical, convolutions slightlj^ flattened. The vessels not in- 
 jected except adjacent to abscess where the surface of the brain was roughened and a 
 small amount of exudate had collected in the pia-arachnoid. 
 
 Longitudinal section of the head through the nares and roof of mouth presented 
 no abnormality and did not reveal the starting point of the abscess. Incisor teeth 
 were quite loose, and irregular in size, shape, and position. 
 
 Subcutaneous and peritoneal fat almost absent. Muscles of the back and abdo- 
 men pale, reddish, and translucent. 
 
 Pleural cavities dry; left lung adherent at the apex and at two or three points to 
 the diaphragm, being bound by quite firm, fibrous adhesions. Lung was small; 
 generally crepitant, and of a reddish pink color. The bronchi and vessels were clear. 
 The bronchi and trachea pale and dry. Scattered through the lung were 8 to 12 
 nodules varying from 2 mm. to 5 cm. in diameter, averaging 1.5 to 2 cm., fluctuat- 
 ing, raised, firmer, slightly tense with a yellow center surrounded by a narrow rim 
 of dark red consolidated lung. These areas were the parts adherent to the diaphragm 
 and apex. On section of such a nodule, in the center was found a core of semi- 
 solid, semi-purulent, cheesy, material about two-thirds the size of the nodule, con- 
 tained in a smooth-walled, cyst-like cavity surrounded by the red, consolidated rim 
 of lung. No miliary nor conglomerate tubercles were found in the consolidated 
 regions. The lymph glands at the hilum of the lung were not large nor caseous. 
 
 The right lung presented the same appearance as left, and contained from 8 to 
 10 nodules. 
 
 Heart. Parietal and visceral pericardial layers were normal. A few cubic centi- 
 meters (3 to 5) of clear, amber, fluid were present. The subepicardial fat almost 
 absent. The heart valves were clear and delicate. The cavities appeared normal, 
 the muscle was semi-translucent, reddish brown; the heart weighed 35 grams. 
 
 Spleen weighed 100 grams, measured 12 x 8 x 2 cm., surface smooth, consistence 
 soft, color dark red ; on section uniform in appearance, not opaque and apparently 
 was normal. 
 
382 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 Liver weighed 175 grams. Dimensions 18 x 12 x 3 cm. Surface smooth and glis- 
 tening. Consistence soft, edge sharp. On section the liver was uniformly dark brown, 
 the lobules not distinct. Over the posterior border of the upper right lobe were a few 
 white pin-point areas of thickening in the capsule. A tapeworm was found in the 
 bile duct and adjacent intestine, and was identified as the "fringed tapeworm," 
 or "liver tapeworm," its technical name being "Thysanosoma actinioides." 
 
 Left kidney. Capsule stripped readily leaving a smooth, brownish surface 
 with a thick cortex (between 9 and 11 mm.). Glomeruli showed as red points; striae 
 fairly well marked, boundary zone visible. The pyramids and pelvis of kidney ap- 
 peared normal. Right kidney had the same appearance as left. Combined weight 
 of kidneys 85 grams. The digestive tract presented no abnormality upon opening it 
 except for the presence of tapeworms. The pelvic viscera, uterus, tubes and ovaries 
 were clear except that a soft parasitic cyst was found attached to the right broad 
 ligament. 
 
 Microscopic report. Paraffin sections. Stained with hematoxylin and eosin. 
 Heart muscle stained well and appeared clear and normal, both fibrils and striations 
 standing out distinctly. Scattered quite thickly through the heart muscle were deep 
 bluish masses, circular, or oval, from three to fifteen times the size of the heart muscle 
 cell. These were seen to be made up of a colorless, thin capsule in which were tightly 
 packed great numbers of comma-shaped, or crescentic-shaped, deeply blue staining 
 masses. There was apparently no reaction in the muscle outside but here and there 
 one gained the impression that these C3'sts containing blue chromatin masses were 
 embedded in a heart muscle cell. 
 
 Lung. Section through nodule. The cavity was seen to be a dilated bronchiole. 
 The plug had fallen from the center, most of the mucosa had dropped off, and there 
 was left a wall containing abundant loose fibroblastic tissue outside of which were a 
 few compressed lung alveoli, passing rapidly into rather congested lung tissue. A 
 second nodule of lung showed on section a bright pink necrotic structureless center. 
 The mucosa was practically entirely gone or else overgrown by an abundant, loose, 
 fibroblastic tissue which occasionally nearly enclosed a small strand or two of colum- 
 nar epithelial cells. The new tissue contained, especially near the necrotic border, 
 great numbers of lymphocytes and of eosinophilic cells. Apparently many of these 
 eosinophiles were mononuclear, although the majority were polymorphonuclear. In 
 the region outside of the organized tissue, more or less compressed lung was found 
 with the alveoli partially filled with an exudate composed chiefly of desquamated 
 epithelial cells and polymorphonuclears. Diagnosis — Organizing bronchiectasis and 
 bronchopneumonia. Other nodules from the lung presented much the same appear- 
 ance. In none of these sections were tubercles found in the consolidated area. 
 
 Spleen showed lymphoid hyperplasia and some phagocytic endothelioid cells, 
 but otherwise appeared normal. The liver showed a definite though not very pro- 
 nounced increase in the cells surrounding the somewhat dilated bile ducts. These 
 cells were in part fibroblasts but chiefly l^-mphoid cells and a few eosinophilic cells. 
 Kidney capsule not thickened; glomeruli appeared normal; slightly congested. 
 Tubular epithelium slightly cloudy though hardly more so than normally. No in- 
 crease in the intertubular connective tissue. Lymph gland (from hilum of lung). 
 Capsule not thickened. Germinal centers well marked. A few of them showed 
 lymphatic hyperplasia with large cells near the middle and some evidence of 
 cell divisions in this region. The sinuses toward the center were widely dilated and 
 
LOCOWEED DISEASE OF SHEEP 383 
 
 contained numerous large desquamated endothelial cells with rather abundant 
 pink cytoplasm. Among them were a number of cells showing the nuclear changes of 
 cell division. Many of these desquamated cells contained what appeared to be hemo- 
 globin. In the cell columns also were found evidences of coll division. The peripheral 
 sinus was not dilated. Diagnosis — Lymphoid hyperplasia. 
 
 Diaphragm. Section was characterized by the presence of about a dozen cysts 
 like those found in the myocardium, the cyst being enclosed within a muscle cell, 
 although there was no reaction nor cell accumulation around the cj^st. A cross sec- 
 tion of peripheral nerve presented no abnormality. 
 
 , Anatomical diagnosis. Extradural basilar abscess; multiple bronchiectatic 
 abscesses in lungs; bronchopneumonia; Cyslicercus tenuicollis adherent to broad 
 ligaments Thysanosoma actinioides infection, biliary hepatitis; emaciation, irregular 
 incisor teeth. Sarcocyslis lenella. 
 
 Case No. 2. Male, yearling sheep on Briggs-Ellis Ranch; Mr. Vestal's house; 
 Big Timber, Montana. September 28, 1903. 
 
 This animal w^as picked out from the same bunch of invalitis as No. 1, it being 
 considered about the worst locoed member of the band except No. 1. The sheep 
 had been at Vestal's Ranch for nearly two weeks, having been brought from a dis- 
 tant ranch on account of their sickness. Like the other sheep in the bunch, this one 
 was undersized, thin, emaciated, walked with a weak gait, the hind legs held rather 
 far apart and the legs being used in a slightly clumsy manner, somewhat suggesting 
 the idea that the animal was walking on stilts. Not all the animals had equal dif- 
 ficulty in walking, some going with perfect ease. Some of the weaker animals looked 
 dull and apathetic. None seemed to be nervous, or excitable, except No. 1. The 
 animals did not show any tremor. They fed naturally, and fairly constantly. Rough 
 tests indicated that hearing and sight were normal and no abnormalities of sensa- 
 tion or of reflexes could be detected on superficial examination. 
 
 It must be noted that the appearance of No. 1 was markedly different from that 
 of the other members of this flock and that the others showed differences among 
 themselves. The only symptoms which seemed fairly constant were (1) thinness or 
 even emaciation, and (2) weakness shown in the slow, uncertain gait and the awkward 
 posture when standing. 
 
 No. 2 being typical of a dozen others in the bunch, was chloroformed, and at the 
 same time the jugular vein and carotid artery were cut. Postmortem examination 
 was made at once at 3 p.m., September 28. 
 
 Autopsy No. 2. The yearling measured from tip to tip about one yard. Weight 
 less than 15 pounds. Emaciation extreme. Skin, eyes, nose, head and ears presented 
 no abnormality. Incisor teeth were loose, and irregular in size and location. The 
 molar teeth were very black. The interstices between the teeth were filled with 
 tough, blackened fiber. Subcutaneous and peritoneal fat very scanty. Peritoneal 
 surface smooth and glistening. In peritoneal cavity were found from 50 to 100 cc. of 
 clear fluid, and eight soft, clear, watery parasitic cysts between 2 and 6 cm. in diameter 
 were between the folds of the omentum. The cysts had no relation to vessels or other 
 structures and were filled with a soft, gelatinous, material containing one short, 
 ringed, cylindrical, worm-like structure, 0.25 to 0.5 cm. in length, 0.25 cm. in diameter, 
 from which fine threads reached out into the jelly. At the rounded end of this worm- 
 like structure was a linear depression. Two or three smaller cysts were found else- 
 where, two being between the liver and diaphragm, and one forming the center of an 
 adhesion between the gall bladder and the small intestine. 
 
384 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 The common bile duct was distended, being as large as a lead pencil. On opening 
 it a flat worm was found completely filling the duct, looped on itself with the head in 
 the lower half of the cystic duct. The rest of the cystic duct was clear. The loops of 
 the worm filled the hepatic duct, extended into several main branches of the hepatic 
 duct and for quite a distance up into the liver and also along the duct of Wirsung for 
 2 or 3 cm. into the pancreas. Loops of the worm also e.xtended into the intestinal 
 canal. 
 
 The liver was of about the same size as that of sheep No. 1. Surface was smooth 
 except for the adherent cyst above described, consistence moderately firm. Just to 
 the left of the median sulcus of the anterior margin was an irregular wedge with Jhe 
 broadest surface toward the edge of the liver, measuring 6x8 cm., rough, firm, of 
 scar-like character, pale, yellowish on section and sharply marked from remainder 
 of liver. On section of liver the main branches of the bile ducts were filled with tape- 
 worms. 
 
 Spleen measured 10 x 6 x 2 cm. It was smooth, soft, and normal on section. Kid- 
 neys were alike, the capsule stripped off readily leaving a smooth surface. On section 
 the cortex measured about 8 mm. The glomeruli were fairly distinct, the pyramids 
 pale, the kidney apparently normal. The adrenals 2 x 1 x 0.75 cm. were bean shaped, 
 with pigment in their surfaces. On section, cortex and medulla were clearly marked, 
 uniform, and apparently normal. Pancreas was soft and friable but presented no ab- 
 normality except for the worm in the duct. Bladder was empty and contracted; the 
 mucosa pale. Aorta elastic and apparently normal. Heart. The pericardial sac 
 contained free within it a cyst like those described above. Pericardial fluid not in- 
 creased. Fat reduced. Surfaces smooth and glistening. The valves were clear and 
 delicate; Foramen ovale closed; myocardium was pale, semi-translucent and brown. 
 The lungs were alike. There was no free pleural fluid. The pleural surfaces were smooth 
 and glistening. The lungs were small, crepitant, cushiony. The bronchi and vessels 
 were clear and pale. On section, the lungs were pink and of uniform appearance ex- , 
 cept for one or two small patches of emphysema. The brain and cord presented no 
 abnormality. The nares and adjacent sinuses were clear throughout. The trachea 
 and esophagus were normal. The paunch was filled with hay and grass well chewed. 
 The other stomachs were noi-mal with the normal odor of gastric contents. In the 
 duodenum were found several heads of tape-worms apparently four in all, with a 
 great many segments. The rest of the intestine contained normal looking contents. 
 The mesenteric lymph glands were enlarged, soft, pale and apparently normal on 
 section. 
 
 Microscopic report. Heart. Section stained well, heart muscle cells for the most 
 part were distinct though slightly granular and a number of the fibers had a wavy 
 contour. Here and there were found cysts, maybe one-half dozen altogether embedded 
 in the muscle and showing no reaction around them. The lung tissue was vesicular 
 and normal. Some of the lung vessels contained an excess of leukocytes. 
 
 Liver. The liver cells were large, somewhat vacuolated and granular. The bile 
 ducts were dilated and lined with high columnar epithelium showing abundant goblet 
 cells. The surrounding tissue was slightly edematous and occasionally peculiar 
 cells and debris were found in the lumen of the bile duct, apparently desquamated- 
 epithelial cells. The lobules could be recognized fairly distinctly; the central 
 two-thirds of the lobule stained deeper than the outer third, the outer third 
 showing cells more vacuolated, paler and more granular and containing more 
 
LOCOWEED DISEASE OF SHEEP 385 
 
 yellow pigment than elsewhere in the lobule. In some instances the nuclei in the 
 outer zone of the lobule had entirely disappeared leaving a yellowish pink granular 
 group of cells. In another block from the liver the cells showed the same changes, 
 and, in addition, there was a definite increase in the fibrous tissue around the 
 bile duct and dense accumulations of cells in this region with indications of 
 rather rapid new formation of a fibroblastic tissue. A nodule was found quite 
 sharply marked off, composed for the most part of newly formed fibroblastic cells. 
 A third block from the liver showed again the accumulation of cells around the 
 bile ducts with a beginning fibrosis extending from the ducts into the liver tissue. 
 The degeneration in the outer zone of the lobule was also seen, though not very dis- 
 tinctly. Another section of liver passed through a nodule of very cellular appear- 
 ance, sending a number of branches into the adjacent liver. In this mass were com- 
 pressed liver cells and strands of liver cells. Great numbers of fibroblastic cells, 
 chiefly young, with large vesicular nuclei, and dense accumulations of lymphocytes 
 together with a small number of polymorphonuclears occurred. There were also a 
 number of eosinophiles. At the edges of this nodule the infiltrating cells were seen 
 in between the liver cells very clearly, but it was very difficult to decide whether the 
 cells were chiefly in the lumina of the capillaries or packed between the capillary wall 
 and the liver cell. Both situations appeared to be commonly occupied. Here and 
 there a capillary was found which undoubtedly was plugged by a mass of small deeply 
 stained cells whose nuclei had the appearance of lymphoid cells. Among these occas- 
 sionally was met a large, pale, oval or rounded nucleus. 
 
 The kidney showed cloudy swelling and slight congestion. The adrenal showed 
 pigmentation in the capsule with, apparently, islands of adrenal cells here and there 
 in the capsule. The large vacuolated cells of the medulla also contained dots of brown 
 pigment. A few cysts were found embedded in the muscle of the diaphragm. 
 
 Anatomical diagnosis. Infection with TInjsanosoma aclinioides; obstruction of 
 common bile ducts, cystic, hepatic, and pancreatic ducts; degeneration (infarction?), 
 of a wedge-shaped section of liver with organization, biliary hepatitis; infection of 
 pericardium, liver capsule and omentum with Cysticercus ienuicollis; loose irregular 
 incisor teeth; emaciation, Sarcocysiis tenella in heart muscle and diaphragm. Cloudy 
 swelling of kidney. Leukocytosis. 
 
 Case No. 3. A flock of 2000 sheep, which had just been driven in from the range 
 to be picked over for the winter, was examined. The flock contained 500 to 800 lambs 
 and yearlings. The sheep herder and the owner (Mr. Vestal) estimated that nearly 
 one-half of the lambs and yearlings were locoed. The examination of the sheep in 
 their corral showed that more than one-half, adults and young ones alike, suffered 
 from coryza and bronchitis. At least one-half of the lambs and yearlings were ema- 
 ciated and moved with a stiff-legged gait. The sheep were more or less sluggish and 
 certainly many of them were very weak. They were not tremulous. They showed no 
 signs of eye or ear defect nor was there any evidence of excitement or mental disturb- 
 ance. They kept in a bunch and did not tend to wander off to the sides of the corral. 
 Xot only the young sheep but manj^ of the older ones were unhealthy looking, one 
 of them being so weak it could not rise to its feet. A lamb about five or six months 
 old which appeared as severely affected as any that could be found was picked out, 
 chloroformed, bled from the carotid, pelted, and examined at once. 
 
 Autopsy A^o. 3. September 29, 1903. Lamb, female. Length about 2| feet from 
 tip to tip. Weight hardly nioi-e than 12 pound.s. Subcutaneous fat practically absent. 
 
386 UNIVERSITY OF VIRGINLA. PUBLICATIONS 
 
 Muscles pale, translucent, reddish brown. Peritoneal surface smooth and glistening. 
 No excess of fluid, one parasitic cyst found in peritoneal cavity. 
 
 Heart. Epicardial fat very slight in amount, surfaces smooth and glistening, 
 valves clear and delicate, foramen ovale closed. Myocardium translucent, reddish 
 brown. The free margin of the left aortic leaflet presented a line of pigmentation. 
 Lungs free from adhesions, pleural surfaces smooth. The color of the lungs in general 
 was pink with here and there small groups of emphysematous cells appearing gray. On 
 the surface of each lung were two or three areas from 0.25 to 1 cm. in diameter which 
 were firmer, irregular, slightly darker red than surroundings and apparently consoli- 
 dated. On section, the lung elsewhere appeared pink, the bronchi and vessels ap- 
 peared clear except for the firm dark red areas. Spleen was small, smooth, soft; 
 the structures showed well on section; condition apparently normal. Liver was 
 small, surfaces smooth, the edge moderately firm and sharp; color, brownish red, 
 semi-translucent. On section, appearance was uniform. The lobules were not dis- 
 tinct. On the convexity of right lobe of liver a pin-head sized whitish fibroid 
 nodule was met with. Kidneys appeared pale and normal but under the capsule 
 there were one or two fibroid nodules, 1 or 2 mm. in diameter embedded in the 
 cortex. Pelvis and ureters clear. Bladder empty. Mucosa pale. Ureters, tubes 
 and ovaries small and normal. Pancreas soft, friable, apparently normal. Diges- 
 tive tract contained normal food in abundance and showed no lesion. Brain and 
 cord apparently normal. No excess of fluid. No adhesions. The sinuses connected 
 with the nose were empty and clear. There was a slight muco-purulent exudate 
 over the turbinate bones. The incisor teeth showed irregularities in position and 
 were loose, otherwise mouth was clear. Mesenteric fat and body fat in general 
 was very great'y reduced. The adrenals were bean-shaped with dark pigmentation 
 over the surface showing the cortex and medulla clearly on section. Hemolymph 
 glands were numerous, pin-head in size. 
 
 Microscopic report. Heart. Striations and fibrillations distinct. ^Muscle cells 
 slightly granular, otherwise apparently normal. Two or three small sarcocysts were 
 found. In two instances the cyst occurred in a Purkinje cell. Lung apparently nor- 
 mal; section from nodule not obtained. 
 
 Liver. The section was distinctly cloudy. The liver cells were large, frequently 
 vacuolar and granular. The bile ducts were distended, though only to a slight degree. 
 The blood in the portal vessels contained an excess of leukocytes, quite a number of 
 which were eosinophilic and in addition there was a distinct increase of lymphocytes in 
 the portal b'ood. The peribiliary tissue was edematous and contained a small number 
 of cells, partly lymphoid, partly eosinophilic. 
 
 Spleen, slightly congested, otherwise normal. The kidney tubules were lined 
 by cells which were markedly vacuolated; otherwise the section was normal, except for 
 the nodule in the cortex. A section through one of the white nodules described in the 
 autopsy report showed that the nodule was embedded in the cortex of the kidney. 
 In the center of the nodule was a small focus of coagulation necrosis with fragment- 
 ing nuclei surrounded by fibroblasts and mononuclear cells, some of which were 
 lymphoid in character, others larger, and like mononuclears. These large and small 
 mononuclear cells, mingled with fibroblasts, extended quite a distance between and 
 compressed tubules. In the nodule were found three chief foci of coagulation necro- 
 sis and two or three smaller ones. The fibroblasts appeared to form a complete cap- 
 sule immediately around the foci of necrosis. Outside of this infiltration became much 
 
LOCOWEED DISEASE OF SHEEP 387 
 
 more diffuse. One or two large cells were met with at the very edge of the area of 
 coagulation necrosis which had an abundance of pink cytoplasm and contained a con- 
 siderable number of nuclear fragments. They did not, however, suggest the giant 
 cell of tuberculosis. The fibroblastic tissue did not seem to be especially rich in 
 capillaries. Among the cells were a good many with eccentric nuclei and rather pink- 
 ish purple cytoplasm, apparently of the plasma cell type but unusually large for 
 plasma cells. Adrenal, apparently normal; diaphragm showed no cysts. Bone marrow 
 showed an excess of giant cells, and of cells of the myelocyte type. Lymph gland 
 showed hyperplasia of the cell nests with crowding of lymph cells in the outer zone 
 of gland. The sinuses in the central part of gland were widely dilated, and contained 
 large vacuolated endothelial cells having a cloudy, degenerating appearance. 
 
 Anatomical diagnosis. Emaciation; irregular incisor teeth; Cysticercus tenuicol- 
 lis in peritoneal cavity; catarrhal inflammation of nares; patches of recent broncho- 
 pneumonia. Inflammatory nodules in kidney. Sarcocystis lenella in heart. Peri- 
 biliary cirrhosis; degeneration of outer zone of liver lobule. Lymphoid hyperplasia. 
 Case No. 4. At Mr. Clifford Kelly's ranch, Hunter's Hot Springs, Montana. 
 The sheep herder brought in a very sick yearling from the range, remarking, 
 "if this is not a locoed animal, I have never seen a case of loco." The animal was 
 thin, weak, stiff-gaited, dull, apathetic, with a rather rough fleece. 
 
 Autopsy No. 4- October 14, 1903. Animal bled to death and autopsied at once. 
 Female sheep, greatly emaciated. Feet were apparently normal. There was an ex- 
 tensive area of extravasation and edema over the buttocks. Subcutaneous fat very 
 greatly reduced. Muscle pale, translucent, apparently normal. Peritoneal surfaces 
 in general smooth and glistening except for adhesions. No excess of fluid. Peritoneal 
 fat greatly reduced. No cysts free in peritoneal cavity. Pleural cavities contained 
 no excess of fluid. No adhesions. Right and left lungs were moderately voluminous, 
 pale, pink, crepitant; vessels clear. On opening into the smaller bronchi a number of 
 fine worms were found together with a considerable amount of thick, viscid, mucus. 
 The worms were approximately an inch long, and as thick as medium or coarse, cotton 
 thread, were motile, white with a dark line running spirally from head to tail. Six 
 were removed from one bronchus. On the surface of lung were one or two raised, dark 
 red, firmer areas not very sharply marked off and consolidated. On section a nodule 
 of consolidation was found to communicate with the bronchus containing worms. 
 Pericardial cavity contained small amount of clear, yellow fluid. Pericardial surfaces 
 smooth and shining. Fat very slight in amount. Heart valves clear, delicate. For- 
 amen ovale closed. Myocardium, pale, brown, translucent. Spleen small, surface 
 smooth, consistence soft. On section, dark reddish brown. Malpighian bodies and 
 trabeculae clearly seen. Liver. Between diaphragm and liver, over the whole of the 
 anterior (ventral) surface were firm adhesions in which were cavities containing 50 
 to 100 cc. of slightly turbid, yellowish, bile-stained fluid together with two or three 
 fairly large, firm, elastic clots 10 or 15 x 1 or 2 cm. in size. This mass of adhesions, 
 etc., was in relation with an ulcerating surface on the liver which showed best on 
 section through the liver. On section, there was found in the middle of the main lobe 
 an ulcer 3 or 4 cm. in diameter, firm, slightly projecting, pale gray, fleshy looking, 
 with irregular margin.s extending deeply into the lobe. In the center of this area was 
 a necrotic rough-walled cavity, bile stained, about 2x3 cm. Elsewhere the liver was 
 brown, moderately soft, and showed little alteration. Gall bladder apparently 
 normal. Bile ducts empt^^ Stomach contained a normal amount ofrfood. The lining 
 
388 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 of the stomach was everywhere smooth and pale. In the upper part of the duodenum 
 were found numerous flat worms, the total length of which amounted to some five 
 or ten meters long. These apparently represented three or four worms which were 
 like the liver worms described previously (fringed tapeworm). Rest of the bowel 
 normal, but contained an excess of sticky mucus. The front teeth were set crooked 
 to the gum, and were loose; mouth and esophagus clear. The mucosa of nasal cavi- 
 ties was injected, slightly ecchymotic and covered with a sticky mucus. The eth- 
 moid and frontal sinuses were clear. 
 
 Kidneys were alike, and appeared normal. Bladder contracted, empty, apparent- 
 ly normal. Internal genitalia apparently normal. Brain and cord presented no 
 abnormality. 
 
 Microscovic report. Heart showed quite a large number of sarco-cysts like those 
 previously described. Most of them were within heart muscle cells. One, however, 
 was found in the space between two groups of muscle bundles. Heart muscle other- 
 wise normal. Lung. The bronchial mucosa stood out clearly and showed no alter- 
 ations. The bronchial walls were clear. The lung, everywhere vesicular except for 
 one small focus in which possibly as many as a couple of dozen alveoli were filled with 
 red blood corpuscles. Among the corpuscles and in the alveolar walls were a moderate 
 number of polymorphonuclear leukocytes. It appeared that the chief infiltration with 
 leukocytes was into the alveolar wall. One or two alveoli contained a great excess of 
 desquamated epithelial cells. In one alveolus these cells were packed together, well 
 stained, and almost looked as if they were growing in the alveolus. 
 
 Liver. Section 1 passed through a necrotic region of liver and showed in the 
 margins great irregular proliferation of bile ducts and a large bile duct with papil- 
 lomatous changes in the mucosa together with infiltration of the surrounding tissue by 
 large and small mononuclear cells, eosinophiles, and eosinophilic mononucleated cells. 
 Around the dilated duct the necrotic liver tissue exhibited regions in which hem- 
 orrhage was abundant, and many regions where very great fibroblast formation 
 was occurring. The section extended from the liver to the diaphragm. Between 
 the liver and diaphragm was necrotic debris in which was considerable fibrin, many 
 polymorphonuclear leukocytes, fragments of nuclei, and yellowish brown mate- 
 rial apparently disintegrated red blood cells. Many of the polymorphonuclears took 
 a bright acid stain. Granulation tissue was forming from the diaphragm and 
 extending into the exudate between liver and diaphragm. Throughout the sec- 
 tion the replacement of liver tissue by a watery and cellular fibroblastic tissue was 
 marked. In this fibroblastic tissue, atypical bile ducts were abundant. Other sec- 
 tions through liver and diaphragm gave findings practically the same as those de- 
 scribed. In addition there were numerous sarcocysts in the diaphragmatic muscle. 
 
 Spleen apparently normal, pulp very cellular. Pancreas. The cells were large, 
 very much vacuolated, at first sight reminding one of the adrenal. The definite ar- 
 rangement into glands and acini was obscured by the tremendous swelling of the 
 cells. There was, however, no evidence of necrosis, the nuclei for the most part were 
 fairly well preserved although they were rather vesicular with dots of chromatin 
 around the margin, and occasionally they were pyknotic. Kidney. Glomeruli un- 
 altered, moderately full, tubules of cortex very cloudy, pale and vacuolated, frequent- 
 ly showing abundant albumin in the lumen. Adrenal apparently normal, capsule pig- 
 mented; eosinophilic cells were seen between cortical cells. The capsule and periph- 
 eral sinus of the lymph gland were apparently normal, the cortical zone was uniformly 
 
LOCOWEED DISEASE OP^ SHEEP 389 
 
 composed of dense masses of lymphoid cells except that here and there a germinal cen- 
 ter stood out as a pale pink focus in the cortex. All of the central sinuses were very 
 widely dilated and contained free cells. The cell columns were reduced corresponding 
 to the dilatation of the sinuses. Under high power the center of one of the germinal 
 centers showed a moderately large amount of slightly stringy, rather homogeneous 
 deep pink hyaline material in which were only a few cells; around these were a number 
 of large, vesicular nuclei, oval or round, which formed several layers not sharply 
 marked and mixed more and more with lymphoid cells as one passed from the center 
 to the periphery. Small masses of interstitial hyaline were also found in the cortex 
 elsewhere than in the cell nests. The cells in the dilated sinuses appeared to be large 
 desquamated epithelial cells which were often phagocytic. The sinuses also contained 
 a moderate number of polymorphonuclear eosinophiles and lymphoid cells. 
 
 Section through a small hemolymph gland about 3 mm. in diameter showed that 
 the peripheral sinus was dilated and packed with red cells, the central sinuses were 
 not nearly so dilated as in the cases previously recorded but most of them were packed 
 with red cells. A distinction into germ centers and cell columns could not be made out, 
 the section appearing to be made of the sinuses distended with red blood cells and of 
 intervening diffuse, cellular tissue in which a light reticulum could be made out. 
 As seen under the high power, the cellular tissue seemed to be chiefly made of cells 
 of a lymphoid type and of variations from this type. Endothelial cells phagocyting 
 red corpuscles were common. Bone marrow showed an increase in polymorphonu- 
 clears, many of which were eosinophilic, and an increase in cells of the myelocyte 
 type. Section through the thyroid showed a number of acini containing bluish pink 
 secretion, the acini being lined by vacuolated cuboidal or low columnar cells. There 
 were many small acini. 
 
 Anatomical diagnosis. Thysanosoma aciinioides infection; abscess of liver with 
 sub-diaphragmatic abscess; fibrosis in liver; vacuolization of pancreas cells and kid- 
 ney; emaciation; loose and irregular incisor teeth; verminous pneumonia, Slrongylns 
 (Meta-strongylus) filaria; Sarcocysiis tenella. Lymphadenitis. 
 
 Partial autopsies were performed upon three of the healthier invalid lambs on 
 Mr. Cliff Kelly's ranch. All three died from experimental doses of cavadine (death 
 camus) administered by Professor Chesnut. 
 
 Autopsy No. 5. This animal was infected with Thysanosoma aciinioides and 
 showed a small caseous-cystic cavity in the apex of the right lung. 
 
 Autopsy No. 6. The fringed tape-worm was present in this animal also, together 
 with organizing bronchopneumonia, and sai'cosporidiosis. 
 
 Autopsy No. 7. No worms were found in a partial autopsy of this animal. Micro- 
 scopically, there were great numbers of sarcocysts in the heart muscle and diaphragm. 
 
 Case No. 8. October 15, 1903. Mr. Clifford Kelly's ranch. A number of badly 
 diseased sheep, regarded as cases of "loco" were confined to a pen and fed with loco- 
 weed for a short while. One was examined, which had been fed for two weeks on 
 freshly plucked locoweed, occasionally receiving also a little alfalfa. Before autopsy 
 it was observed that there were no special symptoms. Pupils were not dilated nor 
 contracted. The animal presented exactly the same features as the other animals 
 which had not been fed on loco. It ate by preference alfalfa but also ate the loco 
 which was put in the corral. Animal emaciated and stiff. Bled from carotid, skinned, 
 and autopsied at once. 
 
 Autopsy No. 8. Very much emaciated animal. Fleece rough and poor. Subcu- 
 
390 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 taneous fat almost absent. Muscles pale, Recti were semi-translucent. Peritoneal 
 cavity contained about 100 cc. of clear yellow fluid. Common bile duct, cystic, 
 hepatic, ami pancreatic ducts were filled with tape-worms and dilated to a diameter of 
 about J inch. The worms extended a very short distance into the duodenum. Liver 
 was smooth and apparently normal except for the dilatation of the ducts. In the 
 omentum were found several gelatinous cysts and one cyst similar to these was found 
 encapsulated on the surface of the liver. This cyst was more or less dried up into 
 a somewhat cheesy mass. Diaphragm clear. Pericardial cavity contained 10 or 20 
 cc. of clear fluid. The surfaces were smooth and glistening. Heart valves delicate 
 and normal. Pericardial fat greatly reduced. Myocardium, pale brownish red, semi- 
 translucent. In the substance of the left ventricle was found a caseating nodule 
 similar to that on the surface of the liver. Pleural surfaces smooth and glistening. 
 Lungs were only moderately voluminous, pink, and crepitant throughout. No nod- 
 ules present. Trachea and bronchi and bronchioles free from mucus and from 
 worms. Vessels at the root of the lungs were clear. On section lungs were normal. 
 .Spleen small, surface smooth, consistence soft. On section dark reddish brown; 
 malpighian bodies and trabeculae well made out. Kidneys were alike. Capsules 
 stripped readily leaving smooth, pale surface. On section, the glomeruli and stria- 
 tions were faintly seen. Pyramids were pale. Mesenteric lymph glands were large, 
 soft, and pale, frequently showing on section a rather dark gray medulla. Adrenals 
 appeared normal. Esophagus clear. The first stomach contained about two or three 
 quarts of food in which could be recognized a very small amount of locoweed in a 
 large amount of hay. All four stomachs and intestines were apparently normal 
 showing a slight amount of rather sticky mucus about the middle of the jejunum. 
 No stomach worms were seen nor any worms in the intestine. The sinuses connected 
 with nose appeared clear, the mucosa pale except that in the frontal sinus was found 
 a fly larva. The front teeth were loose, long, and irregular both in length and posi- 
 tion. The gums appeared normal, pale and firm. There was no evidence of suppura- 
 tion nor of foreign material at the roots of the teeth. The brain and its membranes 
 appeared clear throughout. Surfaces of brain and medulla were pale and normal. 
 No excess of fluid. Convolutions prominent. No sign of pressure. No discoloration 
 of brain or medulla. Internal genitalia appeared normal. Ilemolymph glands stood 
 out plainly, apparently were not enlarged. The intima of aorta was uniform and un- 
 changed. 
 
 Microscopic report. Heart, the striations and fibrillations were distinct, especially 
 striations. The undifferentiated central region of heart muscle cells appeared to be 
 unduly large but the pigmentation was not increased. The section contained a large 
 number of cysts located within heart muscle cells, one was found within a large im- 
 differentiated Purkinje cell. In another section of heart, the nodule described in the 
 autopsy was met with. In the center of the nodule was a mass, apparently the cross 
 section of a parasitic worm or embryo. Around this was bluish purple debris with a 
 space between the parasite and the debris. The purple material ended sharply in a 
 zone of fibrillated, pinkish debris, apparently necrotic heart muscle. This passed over 
 rather sharply into relatively normal heart muscle. In the intermediate zone between 
 the debris and the heart muscle there was fibroblastic tissue with large and small 
 lymphoid cells collected here and there. The growth of fibrous tissue was not uni- 
 form throughout the periphery of the nodule but could be clearly made out at several 
 points. In one or two regions it was definitely becoming flattened in the direction 
 
LOCOWEED DISEASE OF SHEEP 391 
 
 of forming a capsule around the embryo. The mononuclear and polymorphonuclear 
 infiltration was extremely slight compared with the size of the embryo. 
 
 Liver. The structure was not obvious, all of the cells being greatly swollen with 
 corresponding reduction of capillaries, most of which were nearly or quite obscured. 
 The liver cells were swollen, granular, and vacuolated. A second section showed that 
 there was a slight dilatation of the ducts, the duct epithelial cells being large with 
 pale, vesicular, bluish nuclei. Occasionally it appeared that there was a slight degree 
 of edema around the ducts, especially the larger ones, but there was no noticeable 
 fibrosis. In only one or two instances, after searching through two sections, could 
 regions be found in which there was an accumulation of cells around the duct. These 
 cells were chiefly mononuclears of a rather large size with moderately abundant cyto- 
 plasm. "Sj)leen apparently normal. Cytolysis of red cells observed. Kidney showed 
 granular epithelium, otherwise normal. Section of lymph gland showed the cortex 
 with very little differentiation between germ centers and cell columns. The deeper part 
 of the gland showed very great dilatation of the sinuses with reduction in the amount 
 of lymphoid tissue between the sinuses, the result being that this part of the gland 
 looked almost like spongy tissue. It could be seen with particular clearness in this 
 section that the sinuses were lined with large, cloudy, pink cells, frequently cuboidal, 
 containing a large, moderately deeply stained but rather vesicular nucleus. These 
 cells were frequently present free in the sinuses, sometimes singly, sometimes in 
 clumps. The sinuses also contained free lymphoid cells. The large cells occasionally 
 contained a large amount of coppery yellow pigment, especially when the cells were 
 free in the lumen. The appearance of the lymph sinuses, owing to this peculiar ar- 
 rangement of the lining endothelium, suggested at first sight adeno-carcinoma. The 
 blood vessels in the glands were empty or showed only normal contents. 
 
 Anatomical diagnosis. Thysanosoma aclinioides infection of liver and pancreatic 
 ducts; emaciation; loose and irregular incisor teeth; Cysticercus tenuicollis with case- 
 ating cysts in capsule of liver and heart; larva (Oestrus ovis) in right supraorbital 
 sinus. Hyperplasia and phagocytosis in lymph gland. Sarcocystis tenella. 
 
 Case Xo. 9. This was a badly locoed sheep from Mr. Cliff Kelly's invalid band 
 which had been fed on locoweed especially for purposes of experiment but presented 
 no alterations as the result of such feeding, and evidently did not like the weed as a 
 diet. The animal was dull, emaciated, stiff-legged and weak and had a slight coryza. 
 October 15, 1903, was bled from the carotid and examined at once. 
 
 Autopsy No. 9. Fleece rough and ragged looking, front teeth loose and irregular. 
 Superficial examination negative. Fat almost absent. About 100 cc. of clear yellow 
 fluid in peritoneal cavity. Peritoneal surfaces smooth and glistening. Several 
 gelatinous cysts with motile embryos were seen in the peritoneal cavity. The common 
 bile duct, the cystic and hepatic ducts were tightly packed with tape-worms. The 
 diaphragm appeared clear, muscles red, uniform, translucent. Pericardial fluid 10 
 to 15 cc, cleai yellow. Pericardial surfaces smooth and glistening, the fat greatly 
 reduced. Myocardium reddish brown, translucent, valves clear and delicate. For- 
 amen ovale closed. Pleural surfaces dry and pale, free from adhesions. Lungs alike, 
 not very luminous, pink, crepitant, and free from nodules. Vessels at the root of the 
 lung were clear. Trachea and bronchi pale, containing a slight amount of sticky 
 mucus. In the finer bronchioles were one or two small thread like structures appar- 
 ently young worms around which there was very little reaction. Spleen smooth, soft, 
 small. On section, malpighian bodies and trabeculae clearly made out. Liver smooth, 
 
392 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 motlerateh' soft, dark. On section, negative except for dilated bile ducts. Kidneys 
 alike. Capsule stripped readily leaving a smooth pale surface. On section, the cortex 
 was pale and brownish gray. Glomeruli faintly seen. Appearance on section normal. 
 Adrenals and hemolymph glands were like those in the previous autopsy. The bladder 
 empty and apparently normal. Pancreas soft, apparently normal. 
 
 The fourth stomach contained many fine worms which were free on the mucosa. 
 No encysted forms could be made out in the surface of the mucosa. The mucosa of 
 all four stomachs and the intestine was everywhere pale and smooth. The mucosa 
 of the nasal chambers was injected and coated with a slight amount of sticky mucus. 
 The sinuses connected with the nose were apparently clear and normal. The brain 
 and its membranes showed no abnormality. 
 
 Microscopic report. Lung. The section showed vesicular lung tissue. Liver cells 
 were greatly swollen, vacuolar, and granular; the alignment less definitely preserved 
 than usual, capillaries greatly reduced or often collapsed as the result of swelling 
 of liver cells. The cells in the outer zone of lobule were possibly slightly more granu- 
 lar than the others; the nuclei in the outer zone being frequently very pale or even 
 lost. The difference between the outer zone and the rest of the liver lobule was not as 
 conspicuous as in preceding autopsies. Bile ducts showed very little alteration and 
 were inconspicuous; they were not notably dilated and there was no increase in the 
 surrounding connective tissue. Kidney showed slight cloudy swelling of convoluted 
 tubules. Spleen normal. 
 
 Anatomical diagnosis. Thysanosoma actinioides infection; dilatation of bile 
 ducts; granular and vacuolar degeneration of liver cells; emaciation; loose irregular 
 teeth; infection of stomach with wire worms {Ostertagia marsJialli); recent infection 
 of lung with Strongyhis {Metastrongylus) filaria; Cysticercus tenuicoUis. 
 
 Autopsies 10 and 11 were only partial autopsies performed October 15 at Cliff 
 Kelly's ranch, one of them (No. 10) upon an animal which had received a plant poison, 
 the other (No. 11) upon a locoed animal which had been receiving special doses of 
 loco, without appreciable effect. The autopsies disclosed the presence of the bile duct 
 tape-worm and the wire worms in the fourth stomach of each animal and the lung 
 worm apparently fresh in the lungs of the ''locoed" animal. On microscopic exami- 
 nation of the tissues from case No. 11 sarcosporidia were found in the heart muscle 
 and diai)hragm; there was vacuolar and granular degeneration of the outer zone of 
 the liver lobules; the kidney, spleen and stomachs appeared normal. 
 
 The sheep just described were studied during the autumn of 1903, and 
 furnished the basis of a report to the Department of Agriculture. During 
 the summer of 1904 examinations were made of a number of sheep selected 
 by the ranchmen from diseased flocks, and regarded as examples of severe 
 loco disease. Descriptions of these cases follow: 
 
 Olie Chrest of Howie, Montana selected two "locoed" sheep from his herd for 
 examination. The animals were emaciated, and stiff-legged with ragged fleeces. 
 Their front teeth were loose and irregular. They were regarded as typical locoes. 
 Yearling A was bled to death. 
 
 Autopsy No. 20. At autopsy August 23, animal showed absence of fat; there were 
 several yovmg larvae of Oestrus avis crawling over the turbinated bones; there were 
 
LOCOAVEED DISEASE OF SHEEP 393 
 
 small calcified cysts in the myocardium. The liver showed dilated and thickened 
 bile ducts with Thysanosoma aclinioides in the intestine. Worms supposed to be 
 Strongylus fdlicolis were found tightly attached to the mucosa of the large intestine. 
 
 Microscopic report. Heart showed the presence of several sarcocysts. A small 
 structureless mass encapsulated in a fibrous capsule was found in the heart muscle. 
 This cyst, not more than 3 or 4 mm. in diameter was seen at autopsy. Lung apparently 
 normal except for one patch of bronchopneumonia in which there was considerable 
 hemorrhage surrounded by cellular exudate. Liver showed slight vacuolization of 
 the cells in the outer zone of the lobule. No bile ducts appeared in section. Kidney 
 appeared normal. 
 
 Yearling B, of Olie Chrest, was shot on August 2G.and autopsied at once. 
 
 Autopsy No. 21. The animal was thin but not emaciated. The bile ducts were 
 markedly dilated and packed with masses of "fringed tape-worms." The lymph 
 glands of the mesentery were large, soft and grayish brown. Two hair balls about 
 3.5 cm. in diameter were found in the fourth stomach and in addition many wire 
 worms, none of them firmly attached, were found in the fourth stomach. On opening 
 the kidney two calculi of firm brownish material were found in the calices. The nares 
 contained about two dozen small Oestrus larvae about 2 mm. in length. The mucosa 
 was moderately engorged and swollen and covered with thick tenacious muco-pus. 
 
 Microscopic report. Heart unusually thickly studded with sarcocysts of varying 
 size. Lungs clear except for miliary regions in which red blood cells had extravasated 
 into the alveoli. These regions were so numerous as to give a peculiar dotted appear- 
 ance to the section. No leukocytes appeared with the extravasated reds. The same 
 appearance was seen in sections from several different parts of the lung. Liver ap- 
 peared practically normal, except for thickening of a large bile duct. The small 
 bile ducts appeared unaltered. Spleen apparently normal, Malpighian bodies con- 
 spicuous, pulp cellular. Kidney apparently normal. Voluntary muscle showed a 
 number of sarcocysts, not however nearly so numerous as in heart. 
 
 The following cases are interesting as they point to an infectious variet}' 
 of "loco disease." Two years ago (1902) a ranchman (Mr. T.) failed on 
 account of losses from loco disease, his sheep being at the time on the 
 ranges of B. O. Forsyth, of Busteed, Montana. One year later, another 
 rancher (Mr. V. C.) had heavy losses from loco while using the same range. 
 During this year (1904) Forsyth, using the same ranges, found over 1200 
 cases of loco disease among his sheep, two year olds and adults suffering 
 chiefly. He has now moved to another range. He sent three of his most 
 severe cases of loco disease for examination. 
 
 The sheep were by no means in such wretched condition as many others 
 which had been studied, and one or two other ranchmen considered that 
 they were not severe "locoes." They were thin, but not emaciated; only 
 one walked with the usual stiff -legged gait; there was no cough; the fleece 
 was even and thick, and while one was evidently ill, the general appearance 
 and behavior of the other two was not that of ill animals, though they 
 would not be called large or vigorous. 
 
394 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 August 27, 1904, one of Forsyth's sheep was shot and at the same time bled from 
 the carotid. 
 
 Autopsy 23. Postmortem at once. The sheep was thin but not emaciated, there 
 was a heavy infection with Thysanosoma actinioides in the common and hepatic 
 ducts; over fifty-six small wire worms were found in the fourth stomach. The incisor 
 teeth were long. There was a small amount of black sand in the pelvis of the left 
 kidney. Hemorrhagic spots were found in the lungs and there was a hair ball in the 
 fourth stomach measuring about 4 x 2 x 1.5 cm. On microscopic examination small 
 sarcocysts were found in the myocardium; and pin point areas of extravasation into 
 the alveoli of the lung. The liver cells were distinctly vacuolated, the capillaries 
 being indistinct and compressed. Even the small bile ducts were altered, but the 
 change was more marked in the larger ducts. These were distended, frequently 
 filled with exudate and surrounded by cellular and fibroblastic tissue. The fibro- 
 blast formation was only moderate and had invaded the liver tissue to only a slight 
 extent. The cells surrounding the bile ducts were polymorphonuclears, large and 
 small lymphoid cells and fibroblasts. An increased number of polymorphonuclears 
 were present in the portal veins. Occasionally a small duct was found packed tightly 
 with leukocytes so that the wall could hardly be recognized. The spleen showed 
 cytolysis of red blood cells; the kidneys and adrenals were apparently normal. In 
 a section through a lymph gland the sinuses were found dilated, as previously de- 
 scribed, and containing eosinophiles, phagocytic endothelial cells and many granules 
 of brownish pigment, like blood pigment. The voluntary muscle contained a few 
 sarcocysts. Section of the fourth stomach showed no definite evidence of lesion from 
 the wire worms; there was no reaction of an inflammatory character in the mu- 
 cosa or sub-mucosa. Esophagus. Both epithelium and muscle wall appeared to be 
 normal. 
 
 Autopsy 24. A two year old ewe from the Forsyth ranch was shot and at the same 
 time bled from the carotid and autopsied at once on August 27. The animal was 
 in fair flesh, the chief findings being that the common bile ducts and hepatic ducts 
 were packed with Thysanosoma actinioides which also extended far back into the 
 smaller liver duct§. The bile ducts were thickened and dilated and there were pin 
 point hemorrhages into the mucosa. There was beginning necrosis of a wedge-shaped 
 area on the cephalad surface of the right lobe of the liver. Twenty, or more, wire 
 worms were found in the fourth stomach and Oestrus larvae in the supraorbital 
 sinuses. There were small points of hemorrhage in the lungs. On microscopic ex- 
 amination the heart showed a moderate infection with sarcocysts, one of which 
 was found in a large Purkinje cell. The lung and spleen appeared normal. The 
 liver showed very marked changes especially in the region of the capsule of Glis- 
 son. At one place a widely dilated bile duct was cut across showing in the lumen 
 a section through a tape-worm. The structure of the duct wall was practically lost 
 and around the duct there was marked inflammation with necrosis of liver tissue, 
 abscess formation and the evidences of chronic inflammation. Small regions 
 of necrosis were scattered for quite a distance out from the main bile duct and the 
 bile ducts all over the section showed thickening and infiltration around them. The 
 outer zones of lobules were much more affected than the inner two-thirds except near 
 the affected duct described above where lobules were destroyed. Kidney, cloudy. 
 Cross section of lymph gland showed dilated sinuses and hyperplasia, as in previous 
 case. 
 
LOCOWEED DISEASE OF SHEEP 395 
 
 Jacob Hayem sent from his ranch two sheep which he said were badly locoed. 
 The animals were thin and weak, weighing 25 and 35 pounds respectively. The 
 fleece was good, there was no cough nor nasal discharge. There was only slight 
 stiffness in gait. The incisor teeth were unusually long and widely separated. The 
 field note was made that these animals did not present the usual appearance of the 
 so-called "typical locoes" but would pass for specimens of poor stock which might 
 improve if properly cared for during the winter. Compared with the experimental 
 locoes they were pretty healthy looking animals. 
 
 Autopsy 27. At autopsy the smaller animal showed only a very large mass of 
 tape-worm in the middle three-fourths of the small intestine. A field examination 
 indicated that these worms were Taenia expansa. 
 
 Autopsy 28. The same tape-worm {Taenia expansa) was found in large numbers 
 in the intestine of the second sheep in which also the bile ducts contained Thysano- 
 soma actinioides . There was also infection with the Oestrus avis together with ab- 
 scesses in the lung. 
 
 Autopsy 29. August 31. The third sheep from Forsyth, a two year old, had been 
 kept in camp for observation for several days. It appeared rather worse than either 
 of the other two (Autopsy 23 and Autopsy 24), and was very thin. It was, however, 
 active, alert, and free from stiffness. It coughed and sneezed very little, did not pre- 
 sent the symptoms popularly attributed to the so-called typical loco, showing no twitch- 
 ings, and having no tremor nor any special nervous symptoms. Hemoglobin 70 per 
 cent by the Tallquist scale, temperature 102°, respiration 16 to the minute, pulse 116. 
 At autopsy it was found to be infected with Thysanosoma actinioides causing dilata- 
 tion and thickening of the bile ducts. There was Oestrus ovis inflammation to a slight 
 degree and small wire worms were found in the fourth stomach. Cysticercus lenui- 
 cvllis occurred in the peritoneal cavity. The animal was moderately emaciated. 
 
 The eighteen cases described above came from different ranches which 
 were not very close together; the ranchmen were men of experience in 
 sheep raising, and considered themselves, and were considered by their 
 neighbors fully qualified to recognize loco disease. These ranchmen selected 
 from bands of sheep containing many invalids the most typical and pro- 
 nounced cases of loco disease, and turned them over to me for study. It 
 seems hardly possible that every one of the ranchmen could have fallen 
 into the error of selecting for me invalid sheep which more experienced 
 sheepmen would not have looked upon as locoes. In fact, several oppor- 
 tunities arose to check up the diagnosis of one ranchman by that of another, 
 and only minor differences existed between them. It is, then, reasonable 
 to assume that the ranchmen made few, or no, errors of diagnosis, and 
 that the sheep exaqiined were fairly typical representatives of the armies of 
 locoed sheep in Montana. A stud}^ of these sheep ought to reveal the symp- 
 toms characteristic of locoweed poisoning, and the autopsies should bring 
 to light any striking anatomical changes produced by the use of the weed if 
 such occur. It must be stated at once that neither of these objects could be 
 accompHshed. 
 
396 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 Tlie following signs and symptoms were observed: 
 
 1. Emaciation, in the majoritj^ of the animals selected. The other locoes 
 from the same flock were undernourished, often stunted, not always ema- 
 ciated. 
 
 2. Loose irregular incisor teeth, in nine out of eighteen cases. No note 
 was made in the other cases of the condition of the teeth. 
 
 3. Weakness, and stiffness of gait in nearly all the very ill animals but by 
 no means in all animals pointed out by the ranchers as typical locoes. 
 
 4. Dullness and apathy in the ill animals, but not in those less severely 
 diseased. The iller animals were apt to wander off from the flock. 
 
 5. Tremor and nystagmus in one case (No. 1). 
 
 6. Coryza and bronchitis, in some flocks, not in all. 
 
 7. Rough, irregular fleece, occasionally. 
 
 Of these signs, the condition of the teeth is difficult to explain. The 
 fairly constant findings, such as emaciation and under-development, weak- 
 ness and stiffness, dullness and apathy are common to so many forms of 
 disease that they have no value for the dift'erential diagnosis of locoism. 
 The coryza, bronchitis, etc., were sufficiently explained by the autopsy 
 findings. 
 
 The clearest and most detailed clinical picture which the eighteen sheep 
 allow us to draw is about this: The animals suffer from prolonged and pro- 
 gressive malnutrition; in the case of lambs, the animal is undersized; adult 
 animals become thin or emaciated. As malnutrition becomes severe, the 
 animal loses strength and energy, becomes listless, and does not keep up 
 with the flock. As its strength diminishes the animal begins to walk in an 
 awkward manner, the hind legs especially moving stiffly, as if they were 
 parts of a mechanical toy. With these symptoms at least one-half the cases 
 show loose and irregular incisor teeth. Now it is plain that, aside from the 
 condition of the teeth, the above symptoms may result from any one of 
 many causes which bring about malnutrition. 
 
 This forces us to the conclusion that typical and diagnostic symptoms 
 of "Locoism" either do not exist or are so elusive that they escaped both 
 my painstaking examinations and also the observations of the experienced 
 ranchmen who gave their assistance. Inasmuch as the ranchmen were certain 
 that the animals selected for study were severe cases of typical loco disease, 
 there seems to be no escape from the above conclusion. It seems then 
 that it will be either impossible, or exceedingly difficult, to construct the 
 symptomatology of loco disease from animals studied on the ranches. 
 Fondness for the locoweed is commonly regarded as the most constant and 
 characteristic symptom exhibited by locoed animals, but even this was 
 
LOCOWEED DISEASE OF SHEEP 397 
 
 not present in the sheep among which it was especially looked for; these 
 sheep (Cases 8, 9 and 11), preferring other food, (alfalfa), and requiring 
 to be partiall}^ starved in order to make them eat locoweed with an}- 
 freedom. 
 
 Of other queer nervous and mental symptoms, commonly ascribed to 
 loco, there was absolutely no trace in the sheep under consideration, except 
 in one sheep with a brain (subdural) abscess. 
 
 The anatomical findings, like the clinical study, furnished nothing that 
 helped to establish loco disease as a separate and independent disease. In 
 all of the sheep examined there were evidences of more or less severe star- 
 vation. In fourteen cases the " fringed tape worm" (Thysanosotna actin- 
 ioides) was found, and in two others its effects were seen. It caused defi- 
 nite liver lesions in nine instances, of which at least two cases were severe. 
 (Cases No. 4 and No. 24.) Sarcosporidiosis occurred in eight cases out of 
 the nine which were studied microscopically. 
 
 Cysticercus temdcoUis occurred certainly five times, and possibly more 
 often. 
 
 The lung worm was found three times, the stomach worm seven times. 
 Both were probably overlooked more than once. Pneumonia accompanied 
 the presence of the lung worm once or twice. Small bronchiectatic abscesses 
 in the lung occurred twice. An extradural abscess at the base of the brain 
 was found in Case* No. 1; in two instances (Cases Nos. 8 and 20) the 
 remains of an embryo, supposed to be Cysticercus tenuicollis was found on 
 the epicardium; an encapsulated focus of inflammation of unknown origin, 
 possibly tuberculous was found in the kidney in one case (No. 3) ; hj^per- 
 plasia of the lymph glands with dilated central sinuses was observed fre- 
 quentl}^ and there seemed to be leukocytosis in two instances (Cases 2 and 
 23). Sheep fly larvae were found six times, none of the infections being 
 severe. 
 
 Not one of the conditions observed at autopsy could conceivably be due 
 to locoweed poisoning, with the exception of malnutrition. But it is far 
 from certain that the weed was in any degree responsible for the emaciated 
 condition of the sheep. There are other causes at hand to account for 
 the emaciation and weakness. These causes are sufficient, in and of them- 
 selves, to account almost entirety, if not entirely, for the diseases among 
 the sheep examined and also for the diseases among a very large number 
 of sheep in Montana. It is extremely important to understand that the 
 diseases encountered can be clearly explained without any reference to the 
 locoweed whatever, and that the same diseases are known in parts of the 
 world where locoweed does not grow. 
 
398 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 First among the causes responsible for the poor condition of our sheep 
 must be placed insufficient food, and second parasitic diseases. These 
 two causes alone and in various combinations deserve the most careful 
 consideration. 
 
 Insufficient food. It is beyond the scope of this article to discuss in de- 
 tail the subject of sheep feeding. However, there was much evidence ac- 
 quired during 1903 and 1904 which indicated that overstocking of the 
 ranges was common. Frequently it appeared that there were too many 
 animals on the ranges, and at the same tinie that the area of available 
 range was becoming reduced. I was told by some men that the supply of 
 natural forage was much less than it had been twelve and fifteen years 
 earlier, and that the range grass was never given time to attain its growth 
 before it was used again for grazing. I was told that it was not generally 
 customary to rely upon alfalfa and other cultivated crops for food for the 
 stock during inclement weather and at times when the range grass was 
 scanty. I also learned that ranchmen raising large crops of alfalfa suffered 
 relatively small losses from loco disease. In one instance I had a chance to 
 observe that one division of a large flock of sheep grew thin and suffered 
 severely from loco disease on the scanty forage of the plains, while another 
 division of the same flock grew fat and prospered on the richer forage of the 
 uplands. This evidence and more like it makes me agree with those ranch- 
 men who hold that there is not enough natural forage to support all the 
 live stock depending upon it, and that, therefore, malnutrition, or even 
 starvation is not infrequent among the stock. In addition to this it was 
 easy to observe, by watching flocks of sheep feeding, that the small and 
 weak members of the flock are at a great disadvantage. In a flock of several 
 thousand, the sheep, when feeding, are always on the move, staying to- 
 gether, several columns deep. The stronger animals keep to the front and 
 get the best forage; the weaker animals at the rear cat what is left — which 
 is poor rations when the range is short. 
 
 Parasitic diseases. Several of the parasites found in the '"locoed" sheep 
 occasionally produce serious losses. The fringed tape worm {Thysanosama 
 actinioides) , the lung worm, and the fly larvae {Oestrus ovis) are well known 
 scourges. The wire worm of the stomach is a newly discovered parasite 
 and its exact relation to disease is unknown. Since it is very much like the 
 Strongylus contortus, it seems probable that its effects will be similar. The 
 Strongylus contortus causes widespread losses among sheep. 
 
 That sheep are infected with parasites does not mean that they must 
 necessarily die of the infection. The se.verity of the resulting disease de- 
 pends upon a number of factors, such as the age of the animal — ^young 
 animals suffering more than full growns; the general nutrition and health of 
 
LOCOWEED DISEASE OF SHEEP 399 
 
 the animal — under-nutrition and disease of any kind tending to enhance 
 the severity of the parasitic infection. There are also other influential 
 factors which are practically the same as the accessory etiological factors for 
 loco disease, summarized in Section A. Varying degrees of starvation from 
 underfeeding combined with varying intensities of parasitic infection are 
 sufficient to explain the sheep diseases which I have studied, except for the 
 curious condition of the incisor teeth which is unexplained, but seems to 
 run parallel with the fringed tape-worm infections. 
 
 It must be pointed out, that, independent of my autopsy findings, there 
 is strong reason to suspect that the Western ranges are heavily infested 
 with parasitic diseases. The unhygienic conditions of the corrals and water- 
 ing places, the custom of allowing dead sheep to remain unburied, and the 
 unceasing use of the same grazing grounds year after year, without inter- 
 mission, offer conditions favorable to the spread of parasitic diseases. 
 
 In concluding this section of the work, it may be stated by way of sum- 
 mary, that after careful study of severe and typical cases of loco disease it 
 was not possible to collect a group of symptoms sufficiently constant and 
 characteristic to enable the observer to distinguish loco disease from several 
 other diseases; and there was no single characteristic anatomical change 
 found at autopsy, which could be connected with the locowced. 
 
 Moreover we were forced to the remarkable and paradoxical conclusion 
 that the typical and severely "locoed" sheep, selected for us by various 
 ranchmen, were not really suffering from locoweed poisoning, but from 
 combinations of malnutrition and parasitic infection. 
 
 This leads us to the further conclusion that several different diseases 
 pass for "loco disease" on the ranges. Some diseases which pass for "loco 
 disease" have been mentioned above, others will probably emerge upon 
 further study of Western live stock. 
 
 A further important conclusion forced upon us is that there is urgent 
 need for a thorough-going technical medical survey of the ranges, to deter- 
 mine the existing forms of parasitic diseases and their extent, and to devise 
 means to combat them. 
 
 In view of the findings recorded above, relatively little importance at- 
 taches to the answer to the ultimate question as to whether or not the loco- 
 weed is capable of producing a disease, which is independent of other dis- 
 eases. Having found that 100 per cent of severe "locoed" cases examined 
 were suffering from well known diseases other than loco poisoning I sus- 
 pect that the locoweed has very little to do, directly, with the losses among 
 sheep on the western ranges; but the evidence at hand does not justify 
 ' an answer to the ultimate question, as to the existence of simple locoweed 
 poisoning. 
 
400 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 C. FEEDING EXPERIMENTS. 
 
 The campaign of 1903 established the facts that several menacing par- 
 asitic diseases are widely spread among the sheep of Montana; that these 
 diseases, either of themselves, or in combination with insufficient food, are 
 named "loco disease" by the ranchmen, regardless of the type of infection, 
 or its severity; and that whatever symptoms the locoweed may cause can 
 not be recognized accurately in sheep suffering from, parasitic infection and 
 underfeeding. If the effects of locoweed poisoning can be determined, it 
 must be done in some other way than by the examination of sheep which 
 the ranchmen call "locoes." 
 
 The Department of Agriculture directed me to continue the study of 
 the loco problem during the summer of 1904, acting with the advice of 
 Professor Chesnut and in cooperation with Mr. Reese of the Montana Agri- 
 cultural College. It was decided to conduct a feeding experiment, and hold 
 sheep in corrals where locoweed abounded, while others fed on alfalfa were 
 kept as controls. Professor Chesnut, whose prolonged studies of the loco- 
 weed from the botanical side particularly fitted him for the purpose, selected 
 Ten Mile Flat as the site of the experiment, for here the locoweed Aragallus 
 spicatus (Hook.) Rydberg was imusually abundant, and other poisonous 
 plants were absent. 
 
 Ten Mile Flat is a stretch of public land east of the Crazy Mountains and 
 north of Big Timber, Montana. It has the reputation of being one of the worst 
 locoed districts in this part of Montana. The soil is very poor and dry ; there 
 is a moderate amount of alkali, and the streams nearby are alkaline. The 
 forage is quite scanty, a small amount of grass, wire grass and other plants 
 occurring together with large patches of locoweed. From June until autumn 
 the flat is very dry, and is exposed to the full effects of the summer sun. 
 There was no shade where the experiment was conducted. In spite of its 
 bad reputation, large bands of sheep are grazed over this fiat every year. 
 In the early spring of 1904, there was a moderate amount of grass to be 
 found over the region, but this was quickly removed by two bands of from 
 three to five thousand sheep apiece, which passed over this region before 
 the middle of June. Another band was taken over soon after, leaving very 
 little nutritious forage behind. Inquiries were made, but it could not be 
 ascertained whether these bands suffered particularly from loco poisoning. 
 
 A large area with an abundant growth of locoweed was selected for use 
 during the experiment. The objects of the experiment were: (1) To de- 
 termine whether sheep can be poisoned by the locoweed when it is used as a 
 food. (2) To determine the signs, symptoms and anatomical changes re-' 
 
LOCOWKED DISEASE OF SHEEP 
 
 401 
 
 suiting from loco poisoning, in case such poisoning can be brought about. 
 (3) To determine how soon appearances of poisoning occur after the animals 
 begin to feed on the plant. (4) To determine what diet is preferred by 
 animals which have once learned to eat the locoweed. (5) To determine the 
 relative importance of the various factors which the studies of 1903 had 
 indicated were of influence upon the disease. These factors were age, 
 general liealth, salt diet, partial starvation, and infections with sheep 
 parasites. 
 
 Forty-three yearlings and nineteen ewes with their eighteen lambs were 
 obtained from Mr. Paul VanCleve of Melville, Montana. Only healthy look- 
 ing animals were taken. They were of medium size for their age, and were 
 of mixed breed. The animals were dosed thoroughly with thymol and 
 creosote in order to free them from intestinal parasites so far as possible; 
 were brought to the experimental camp and placed in corrals, a numbered 
 ear tag being attached to each animal. 
 
 Four pounds of alfalfa hay was taken to be a sufficient day's ration for 
 one healthy sheep, and a supply of alfalfa hay was kept with scales beside 
 the corrals, the rations for each corral being weighed out daily. Water was 
 kept in the troughs in the corrals, the troughs being filled twice a day. As 
 often as the forage in a corral was used up, the animals were moved to 
 fresh grazing ground. 
 
 The sheep were kept in eight groups which received food as shown in 
 Table I. 
 
 Received: alfalfa 4 
 pounds per head ; 
 salt ; no fresh for- 
 age; no locoweed. 
 
 GROUP IV 
 
 (5 yearlings) 
 
 Received: alfalfa, 
 4 pounds per 
 head; salt; fresh 
 forage and loco- 
 weed . 
 
 Received: alfalfa, 4 
 pounds per head; 
 no salt; no fresh 
 forage; no loco- 
 weed. 
 
 Received: alfalfa, 2 
 pounds per head; 
 salt; no fresh for- 
 age; no locoweed. 
 
 GBOCP V 
 
 (5 yearlings) 
 
 Received: alfalfa 4 
 pounds per head; 
 no salt; fresh for- 
 age and locoweed. 
 
 GROUP VI 
 
 (10 yearlings; 9 ewes 
 and 8 lambs) 
 
 Received: alfalfa 2 
 I pounds per head; 
 salt; fresh forage 
 and locoweed. 
 
 GROUP vn 
 
 (4 yearlings; 5 ewes; 
 
 5 lambs) 
 
 Received : no al- 
 falfa; salt; fresh 
 forage and loco- 
 weed. 
 
 GROUP VIII 
 
 (4 yearlings; 5 ewe 
 5 lambs) 
 
 Received: no al- 
 falfa; no salt: 
 fresh forage and 
 locoweed. 
 
402 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 Groups I, II and III were kept in corrals in which there was nothing 
 for them to eat except the alfalfa hay which was given to them daily. 
 Groups IV, V and VI had the chance to eat locoweed and other growing 
 plants in addition to the daily ration of alfalfa. Their corrals were moved 
 as fast as the locoweed and other grasses were used up. Groups VII and 
 VIII fed only on the locoweed and grasses to be found in the corrals. These 
 corrals were constantly being moved so as to provide pasturage for 
 their occupants. Groups I, III, IV, VI and VII received salt at frequent 
 intervals.* 
 
 The animals were put in the corrals and the experiment started on July 
 15, 1904 and continued until September G.f 
 
 The animals were closely watched to determine when they first began 
 to eat the loco. On July 18 it was discovered that one ewe and one lamb 
 in Corral VIII had been eating the weed and by evening a considerable 
 quantity had been consumed. All the nutritious forage had been eaten out 
 before the loco had been touched, and it was soon noticed that all the ewes, 
 lambs and yearlings in corrals VII and VIII were eating the loco freely. 
 
 The sheep which received hay also, did not take to the loco so readily, 
 and it was July 31 before there was any evidence that the animals in Cor- 
 rals IV, V, VI were eating the weed. They did not begin to eat the loco- 
 weed until they had cleared out all the other green forage in the corrals. 
 After they once began to eat the locoweed they showed quite a preference 
 for it whenever they were subsequently placed in a fresh corral. However, 
 they always ate abundantly of alfalfa, when it was furnished, and also of 
 the other forage in the corrals, never confining their diet to the locoweed, 
 even after they had formed the habit of eating it. 
 
 The experiment thus demonstrated perfectly clearly that sheep can be 
 made to eat the locoweed, and that when they once begin eating it, they like 
 it as much as other food, and possibly prefer it. It also appeared that sheep 
 u'ill not touch the weed while they receive a plentiful supply of green forage, 
 but will take it if they are starved, or if they are fed on alfalfa hay and al- 
 lowsd to graze where locoweed is the only fresh plant. 
 
 ♦The assistance of Mr. Reese of the Montana Agricultural College, in caring for 
 the animals, weighing them, moving corrals, etc., was of great value. 
 
 f while this experiment was in progress a second feeding experiment was con- 
 ducted in a distant part of Montana. Five lambs and four ewes, all healthy animals 
 were kept in corrals abounding with locowped from June 10 to September 16. The 
 experiment was conducted at White Sulphur, Montana, on the ranch of Mr. C. W. 
 Cook from whom the sheep were obtained. The results agreed with those obtained 
 at Ten Mile flat, but it was impossible to give close continued attention to the ani- 
 mals, and the eSperiment is therefore not set forth in detail. No result was obtained 
 which in any y/^Y conflicted with 'the results obtained at Ten Mile Flat. 
 
LOCOWEED DISEASE OF SHEEP 403 
 
 The following field notes indicate the general condition of the animals: 
 
 August 7, 1904. Groups I and II. Sheep are not large, but are in fair flesh and 
 appear healthy; one or two have cough, not very severe, with sneeze. If there is any 
 difference between the groups it is hardly noticeable, possibly the unsalted sheep are 
 slightly fatter than the salted. Quite a lot of hay is left on the ground. All fresh 
 plants in corrals have been eaten. 
 
 Group III (I alfalfa, no locoweed) can hardly be distinguished from Group I 
 and II by their appearance. Sheep not quite so fat, but nearly so. Cough is, however, 
 distinctly more pronounced. Not a wisp of hay left in the corral. Three of the five 
 sheep sneeze, cough, and have nasal discharge. Flies seem to be troubling the noses 
 of the sheep a good deal this morning. 
 
 Groups IV and V (alfalfa and locoweed). About as much hay left on ground as 
 with I and II. No appreciable difference between the sheep of Group IV and those 
 of Group V. About one-half the bunch have a cough and sneeze, etc., as with I, II 
 and III. Locoweed and other grasses (except wire grass) have been completely 
 eaten off. Animals look as well as or better than I and II. 
 
 Group VI (half rations plus locoweed). The yearlings, like those in the other 
 groups, are undersized, and in this corral they are thin and scrawny, but not ema- 
 ciated. The lambs (May lambs) are hardly one-half the size of June lambs recently 
 seen in a healthy flock. The animals in Group I-VIII are suffering with the heat, 
 and stand panting, with their heads together and near the ground, to avoid flies. 
 
 A small amount of alfalfa is still uneaten. The loco and grasses are being eaten. 
 Certainly one-half the bunch have the cough, etc., as above described. Lamb No. 
 55 in corral VI has very severe cough, etc., and is distinctly weak; would be called 
 a fairly severe "loco" by the average ranchman. Lamb No. 52 in corral VI seems 
 weaker than No. 55, but does not cough, though his nose is filled with mucus. No. 52 
 and No. 55 do not run off with the rest of the bunch, but stay and let one come up 
 to them. Every lamb in this corral has severe cough, eyes stuffed with mucus, ex- 
 cept one larger and sturdier lamb. 
 
 Groups VII and VIII (sheep on loco without alfalfa). Sheep are poorer than the 
 others; some are actually emaciated. Lambs even smaller than those in corral VI. 
 No. 46 (lamb) has in addition to cough, etc., an open ulcer on left side of face opposite 
 middle of cheek. In this corral the cough is found in nearly every animal, and is 
 more severe than in the other corrals. 
 
 To generalize about the sheep. The day is very hot and the animals are sluggish, 
 staying in groups with heads together or lying in corners and under the drinking 
 troughs. None of the animals are what would be called first class sheep; all are small 
 and scrubby. The yearlings are hardly larger than some lambs recently seen, and 
 the lambs are not more than half size. The yearlings and lambs have grown extremely 
 little. In each corral the animals are coughing, about one-half the animals in Group 
 I, II and III being affected, more in Group IV and in the last two corrals pretty much 
 every animal. In the last two corrals animals seem about half starved and the cough 
 is much more severe. Several of the starved animals with this cough are what would 
 be called "locoes" by ranchmen. 
 
 The cough, etc., affecting the sheep in Groups VI, VII and VIII became 
 so severe that the animals began to die, and it looked as if the experiment 
 
404 UNIVERSITY OF A'IRGINIA PUBLICATIONS 
 
 would be upset by this disease killing out the animals in the two most im- 
 portant loco pens — Groups VII and VIII. It was found necessary to build 
 up the general health of the sick animals by abundant rations of alfalfa. 
 This was continued for eight days, by which time the animals had improved 
 sufficiently to allow the experiment to be resumed. 
 
 The following notes were made on August 18, the day after the experi- 
 ment w^as resumed. 
 
 Groups I and II. All animals look well, no stiffness observed on motion; over 
 half of them have occasional cough, and a little mucus from the nose; ej^es are clear, 
 and animals seem little troubled by cough. 
 
 The stiff stems of alfalfa have remained uneaten. Food given two and a half 
 hours ago is eaten except for the stiff stems. Six sheep — some salted, some unsalted — 
 are still eating. Very little difference apparent between salted and unsalted animals. 
 Possibly unsalted are eating longer. 
 
 Group III. Animals are in fair trim, eyes clear, but all have cough and sneeze, 
 which gives some distress. Almost every blade of hay given this morning is eaten, 
 and all five animals are picking at what remains. No hay at all is left from yesterday. 
 
 Groups IV and V. Put in new corral of loco after 6 p.m. yesterday. This morning 
 (8.30), in upper part of corral loco is eaten down, seed tops and leaves eaten, occa- 
 sionally seed stalk left. In lower tvvo-thirds of corral, loco still abundant. 
 
 These bands of sheep (IV and V) are the best looking of all, the sheep are in good 
 flesh, ej^es are bright; they are but little troubled by the cough, although most of 
 them have it, and are the nimblest and most active of any band. Possibly, as with 
 the sheep receiving full hay, the unsalted are a trifle fatter than the salted. One 
 salted yearling wether is a trifle stiff and is more troubled by the cough than the 
 others. 
 
 Group VI. .So far as can be determined, the yearlings are as well off as those in 
 pen No. Ill, both as regards general condition, flesh and cough. The ewes are a trifle 
 thinner than the yearlings. The lambs are pretty badly off, Nos. 48 and 55 and 
 another lamb are especially weakly, their noses stuffed up, eyes bleary and dull. 
 All three lambs are undersized, weak and stiff in gait, and listless. Lamb No. 51 is 
 twice as large as the others, seems better, but suffers more from cough than the 
 yearlings. This lamb has all along eaten about double his share; another lamb is 
 also large and in fairly good condition. Four of the seven lambs are hardly any 
 larger than they were when received; the other three are undersized for their age but 
 much better off than the smaller ones. 
 
 After feeding on full hay for eight daj's in order to relieve the cough, this bunch 
 was turned into a new corral at 11 a.m. yesterday. The sheep had stopped picking 
 the alfalfa which had been fed at 6 a.m. and a good deal still remained on the ground, 
 the sheep being collected in groups with heads together. Wheji turned into the new 
 corral, all animals at once began to graze eagerly, and continued for over an hour eating 
 grass and loco as it was found. The ewes and yearlings seemed to prefer the pods 
 and the lambs ate only the leaves of the locoweed. This morning over nine-tenths 
 of all loco is gone from the corral while not one-half of the grass seems to be gone. 
 Though careftd observations xcere made yesterday and this morning, absolutely no effect 
 could be seen in the sheep or lambs as the result of the weed, in spite of the fact that the 
 
LOCOWEED DISEASE OF SHEEP 405 
 
 animals have had more loco than they could eat, all at once, and after eight days of ab- 
 stinence from the locoweed. 
 
 In addition to grazing, this band has eaten about all of the alfalfa this morning. 
 
 Groups VII and VIII. These sheep have improved greatly in the last eight days 
 on their full hay ration. The ewes and yearlings are still the thinnest lot of all, but 
 have improved greatly, being less suffocated, having less bloody mucus from nose, 
 less cough and sneezing, and having gained distinctly in flesh. The animals are still 
 moie stuffed up than those in the other corrals. The lambs, without exception, are 
 bunged up with rhinitis; eyes and face swollen, eyes and nose running, eyes dull, gait 
 stiff and slow, most of them very weak and thin. 
 
 This band after eight days on hay, was turned into a new corral, about 10 a.m. 
 yesterday, after they had stopped feeding on hay. At once all began grazing, eating 
 loco by preference, but also other grasses; ewes and yearlings eating the seed tops, lambs 
 the leaves. After one hour they stopped grazing until evening. Absolutely no effect 
 could be noted in any sheep as the effect of eating the plant. 
 
 This morning not one loco plant can be found, and in several cases the ewes and year- 
 lings have been seen digging at the root, but apparently they have not eaten the plant 
 below the surface of the ground. The corral still contains about one-quarter to one- 
 third of the grasses and other plants. 
 
 The facts of special interest that the experiment afforded up to this 
 time were, that the animals were eating the locoweed, that their general 
 condition was pretty poor, that many of them suffered from cough and rhi- 
 nitis and that some of the animals with cough would pass as locoed animals 
 with more than half the ranchers. The condition was studied, and the diag- 
 nosis was made that the animal was suffering from the sheep fly disease, a 
 diagnosis which was confirmed by autopsy. It was noticed particularly that 
 this disease affected animals in every one of the corrals, those receiving no 
 loco as well as those receiving loco. It was also noticed that the animals 
 receiving the greatest amount of food suffered less severely than animals 
 on insufficient rations; thus the animals receiving four pounds a day of alfalfa 
 and allowed to graze freely on loco stayed in the best condition, the animals 
 receiving four pounds a day of alfalfa alone did almost as well. The animals 
 receiving half rations of alfalfa either with or without loco were more severely 
 diseased. The animals receiving no alfalfa, but scraping a bare subsistence 
 by grazing on the insufficient forage and loco, were the ones most severely 
 diseased. No difference could be seen in the animals receiving salt and in 
 those receiving no salt, as far as this disease was concerned. So severe was 
 the outbreak of sheep fly disease, that the experiment was discontinued for 
 eight days, as noted above, and the animals were kept in their corrals and 
 fed abundantly with alfalfa hay. The symptoms promptly abated, and the 
 experiment was resumed. 
 
 It is interesting to note that up to the time of interrupting the experi- 
 ment, certain groups of animals had been receiving an abundance of loco- 
 
406 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 weed without manifesting any symptoms that could be attributed to the 
 action of the weed. 
 
 When the experiment was interrupted, it might have been expected that 
 the animals would show symptoms from being suddenly deprived of the 
 weed, just as morphine habitues, alcohoHcs and tobacco smokers show 
 symptoms when suddenly deprived of their drugs. This did not occur with 
 the sheep, and they were carefully watched in order to observe any manifes- 
 tations of this nature. On the contrary, the improvement in the condition 
 of the sheep when their diet was increased was almost immediate and re- 
 sembled nothing so much as the improvement which takes placp in a half 
 starved animal when it is placed upon a proper diet. 
 
 When the experiment was resumed, another interesting observation 
 was made: The animals were turned back upon the abundant loco fields 
 after an abstinence from the weed lasting for eight days. It is a common 
 impression that drug users exhibit symptoms when they are suddenly put 
 upon full doses of their drugs after abstinence. This did not occur with the 
 sheep. They were turned into the corrals with loco about an hour after 
 they had finished eating the alfalfa hay which had been given them. They 
 had left some alfalfa hay uneaten, and were lying around in the corners of 
 the corrals. When turned into the corral with fresh forage, they at once 
 began to graze, eating loco and other plants for an hour and a half. At no 
 time did any animal exhibit a single symptom that could be attributed to 
 the weed. 
 
 Another very interesting observation was made during this infection 
 .with the sheep fly. The animals badly infected with these parasites pre- 
 sented the most typical pictures of loco disease. On turning to the descrip- 
 tion of sheep Hy disease, the Western rancher might well think that the 
 writer of the book was confused and was writing a description of the loco- 
 weed disease. It must be remembered, however, that sheep fly disease 
 occurs all oyer the world, and the symptoms have been described as char- 
 acteristic for animals which are entirely beyond the reach of locoweed. 
 
 The following description taken from Neumann's Parasites and Parasitic 
 Diseases of the Domesticated Animals, 1903, pp. 568-570, is inserted in order 
 to make this clear: 
 
 "it (the sheep fly) hides in holes and crevices in the walls of the sheepfolds, which it 
 leaves when coupling time has arrived and the temperature is sufficiently high. It then 
 flies in a lively manner to greater elevations, and rests on rocks warmed by the sun. 
 The fecundated female now goes in search of flocks of sheep, which are afraid of its 
 approach, and to avoid it lie down, bury their noses in the dust between their fore- 
 feet, or are huddled together with their heads down. According to Bracy-Clark, 
 
LOCOWEED DISEASE OF SHEEP 407 
 
 ^hey raise clouds of dust to deceive their enemy. It is during rumination that the 
 insect finds a particularly favorable time for depositing its progeny. Its small size, 
 gray color, and the rapidity of its flight, do not allow its ovulation to be observed; but 
 there can be no doubt that it does not take place on the nose of the sheep. As soon, 
 in fact, as these animals have been touched by the Oestrus, they become excited, 
 run in every direction, hold down their noses and rub them against the ground or 
 against their feet; often look anxiously around them, sneeze and snort, and seek 
 ditches, furrows and dusty roads. Owing to the repeated rubbings, the nostrils are 
 
 often abraided and inflamed Symptoms. — It is usual to find three or 
 
 four larvae of the Oestrus in the frontal sinuses of sheep, which, during life, had not 
 given any indication of their presence. They rarely occasion any morbid disturbance, 
 unless they are numerous and advanced in development at the commencement of 
 spring. The first sign of their presence is a discharge, often unilateral, at first clear 
 and serous, then thick and mucus, from the nostrils. Then there are frequent sneez- 
 ings and snortings, accompanied by the expulsion of the mucus, and sometimes of 
 the larvae. Later the animals throw the head upwards, often shake it, rub the nose 
 on the ground, against some part of the body within reach, or with the forefeet. As 
 the malady progresses the sheep hold their heads low, lift their limbs high in move- 
 ment, as if walking in water— their gait resembling that of horses affected with im- 
 mobilitie. Sometimes they suddenly throw up the head, carry the nose high, then 
 move it convulsively. From time to time they stagger and are attacked with vertigo, 
 but they do not turn in a circle. In more serious cases there is dyspnoea, the upper 
 air-passage being obstructed by the larvae or the inflammation of the pituitary mem- 
 brane. The eyes are red and lachrymose. The disease may be more complicated, 
 the animals losing their appetite and their condition; they grind their teeth; foamy 
 saliva flows from their mouth; the eyes pirouette in their orbits; and convulsions set 
 in, then death ensues, sometimes in six to eight days after the appearance of the 
 first symptoms The common saying that a whimsical person is 'mag- 
 goty,' or has got 'maggots in the head,' perhaps arose from the freaks of sheep affected 
 by these larvae. 
 
 "But it is rare that the malady reaches this paroxysm; it continues for a long time, 
 and generally — the larvae being ejected one after another — the symptoms gradually 
 subside, until they disappear altogether." 
 
 On September 6 the experiment was closed having lasted fifty-three 
 days. The animals at that time had eaten bare a wide patch of loco. The 
 total area covered by the sheep feeding on loco was: Groups IV and V, 
 57,894 square feet; Group VI, 289,854 square feet; Groups VII and VIII, 
 387,084 square feet. The corrals varied from 16,000 to 48,000 square feet 
 in size. 
 
 The animals did not thrive on Ten Mile Flat, and did not do nearly so 
 well as the original band (3,200), from which the animals were selected for 
 experiment and which were kept on the mountain side where the forage 
 was fairly abundant, and living conditions better. Even in this band, how- 
 ever, there were one or two hundred animals undersized, stiff-legged and 
 evidently suffering from sheep fly disease. 
 
408 
 
 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 The following tables show the weights in pounds of the animals when-^ 
 the experiment was begun and the weights at the close of the experiment 
 or at the death of an animal, with the average change in weight for each 
 group. 
 
 Group I, receiving daily 4 pounds of alfalfa per head and salted 
 regularly. 
 
 
 
 
 TABLE II. 
 
 TAG NO.* 
 
 INITIAL 
 WEIGHT 
 
 FINAL 
 WEIGHT 
 
 ALTER- 
 ATION IN 
 WEIGHT 
 
 REMARKS 
 
 
 pounds 
 
 pounds 
 
 1 pounds 
 
 
 14 
 
 68 
 
 71 
 
 + 3 
 
 All of grouj) were yoarlings. 
 
 31 
 
 70 • 
 
 ■74 
 
 1 + 4 
 
 
 4 
 
 58 
 
 59 
 
 i + 1 
 
 
 5 
 
 61 
 
 73 
 
 1 + 12 
 
 
 10 
 
 73 
 
 73 
 
 :' + 
 
 
 Total 
 
 330 
 
 350 
 
 + 20 
 
 Average increase 6.06 per cent. 
 
 * Each animal was numbered with an ear tag. 
 
 (Jroup II, receiving daily 4 pounds of alfalfa per head, but no salt. 
 
 TAG NO. 
 
 INITIAL 
 WEIGHT 
 
 FINAL 
 WEIGHT 
 
 ALTER- 
 ATION IN 
 WEIGHT 
 
 REMARKS 
 
 
 
 pounds 
 
 pounds 
 
 pounds 
 
 
 
 6 
 
 68 
 
 72 
 
 + 4 
 
 All of group were yearlings. 
 
 
 34 
 
 74 
 
 81 
 
 + 7 
 
 
 
 24 
 
 61 
 
 58 
 
 - 3 
 
 
 
 33 
 
 72 
 
 84 
 
 ! + 12 
 
 
 
 43 
 
 77 
 
 81 
 
 1 + 4 
 
 
 
 -^24 
 
 
 
 Total 
 
 352 
 
 376 
 
 Average increase 6.81 per cent. 
 
 
 Group III, receiving daily 2 pounds of alfalfa per head, and salted 
 regularly. 
 
 TABLE IV. 
 
 ALTER- 
 ATION IN 
 WEIGHT 
 
 15 
 
 66 
 
 68 
 
 + 2 
 
 All of grouj) were yearling.s. 
 
 37 
 
 66 
 
 72 
 
 + 6 
 
 
 40 
 
 67 
 
 71 
 
 + 4 
 
 
 18 
 
 74 
 
 73 
 
 - 1 
 
 . 
 
 36 
 
 77 
 
 • 81 
 
 + 4 
 
 
 Total 
 
 350 
 
 365 
 
 + 15 
 
 Average increase 4.28 per cent. 
 
LOCOWEED DISEASE OF SHEEP 
 
 409 
 
 Group IV receiviujij; daily 4 pounds of alfalfa per head, salt and locoweed. 
 
 TABLE V. 
 
 TAG NO. 
 
 INITIAL 
 WEIGHT 
 
 FINAL 
 WEIGHT 
 
 ALTER- 
 ATION IN 
 WEIGHT 
 
 REMARKS 
 
 
 pounds 
 
 pounds 
 
 poujids 
 
 
 
 2 
 
 67 
 
 73 
 
 + 6 
 
 All of group were yearlings. 
 
 
 21 
 
 60 
 
 71 
 
 + 11 
 
 
 
 41 
 
 78 
 
 83 
 
 + 5 
 
 
 
 12 
 
 62 
 
 70 
 
 + 8 
 
 
 
 42 
 
 62 
 
 68 
 
 + 6 
 
 
 
 Total 
 
 329 
 
 365 
 
 + 36 
 
 Average increase 10.94 per cent. 
 
 Group V, receiving daily 4 pounds of alfalfa per lunitl, locoweed, etc., but 
 no salt. 
 
 TAG NO. 
 
 INITIAL 
 WEIGHT 
 
 FINAL 
 WEIGHT 
 
 ALTER- 
 ATION IN 
 WEIGHT 
 
 
 17 
 29 
 
 23 
 
 1 
 
 32 
 
 pounds 
 
 70 
 73 
 73 
 70 
 57 
 
 pounds 
 
 77 
 83 
 85 
 80 
 69 
 
 pounds 
 
 + 7 
 + 10 
 + 12 
 + 10 
 + 12 
 
 Ail of grou}) wero yearlings. 
 
 Total 
 
 343 
 
 394 
 
 + 51 
 
 Average increase 14.86 per cent. 
 
 Group VI, receiving daily 2 pounds of alfalfa per head; salted regularly 
 locoweed. 
 
 TABLE vir 
 A, yearlings 
 
 TAG NO. 
 
 INITIAL 
 WEIGHT 
 
 FINAL 
 WEIGHT 
 
 ALTERA- 
 TION IN 
 WEIGHT 
 
 REMARKS 
 
 11 
 
 35 
 
 38 
 
 19 
 
 9 
 
 3 
 
 8 
 
 26 
 
 16 
 
 27 
 
 pounds 
 
 76 
 77 
 73 
 68 
 75 
 60 
 68 
 76 
 75 
 71 
 
 pounds 
 
 89 
 84 
 76 
 61 
 80 
 64 
 73 
 80 
 79 
 67 
 
 pounds 
 
 + 13 
 
 + 7 
 
 ^^ 
 
 + 5 
 + 4 
 + 5 
 + 4 
 + 4 
 - 4 
 
 
 Total 
 
 719 
 
 753 
 
 + 34 
 
 Average increase 4.72 per cent. 
 
410 
 
 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 TABLE VII— Continued 
 B, ewes 
 
 TAG NO. 
 
 INITIAL 
 WEIGHT 
 
 FINAL 
 ■ WEIGHT 
 
 ALTERA- 
 TION IN 
 WEIGHT 
 
 REMARKS 
 
 70 
 
 93 
 
 86 
 
 - 7 
 
 
 71 
 
 84 
 
 97 
 
 + 13 
 
 
 84 
 
 74 
 
 78 
 
 + 4 
 
 
 80 
 
 71 
 
 81 
 
 + 10 
 
 
 73 
 
 82 
 
 SO 
 
 _ 2 
 
 
 76 
 
 98 
 
 105 
 
 + 7 
 
 
 75 
 
 77 
 
 78 
 
 + 1 
 
 
 78 
 
 68 
 
 80 
 
 + 12 
 
 
 67 
 
 79 
 
 81 
 
 + 2 
 
 
 Total 
 
 726 
 
 766 
 
 + 40 
 
 1 Average increase 5.5 per cent. 
 
 C. lambs 
 
 48 
 
 ! 25 
 
 20 
 
 51 
 
 1 27 
 
 32 
 
 52 
 
 22 
 
 IS 
 
 53 
 
 ! 24 
 
 26 
 
 q5 
 
 i 17 
 
 20 
 
 61 
 
 30 
 
 m 
 
 62 
 
 21 
 
 2U 
 
 03 
 
 30 
 
 37 
 
 rotal. 
 
 196 
 
 204 
 
 - 5 Died Ausast 26. 
 + 5 I 
 
 — 4 Died August 7. 
 
 -I- 2 Killed September 1. 
 
 + 3 I Killed September 1. 
 
 + I 
 
 + 7 
 
 Average increase 4.08 per cent. 
 
 Total initial weight of Group VI 1641 pounds 
 
 Total final weight of Group VI 1723 pounds 
 
 Total alteration in weight Group VI 82 pounds increase 
 
 Average increase in weight, Group VT 4.99 per cent increase 
 
 Group VII, receiving no alfalfa; salted regularly: fed on locoweed. 
 
 TABLE VIII 
 A, yearliiigs 
 
 TAG NO. 
 
 1 INITIAL 
 WEIGHT 
 
 1 
 
 FINAL 
 WEIGHT 
 
 
 pounds 
 
 pounds 
 
 39 
 
 \ 76 
 
 74 
 
 25 
 
 (72) 
 
 
 20 
 
 i 66 
 
 69 
 
 22 
 
 74 
 
 70 
 
 Total 
 
 , 216 
 
 213 
 
 ALTERA- 
 TION IN 
 WEIGHT 
 
 pounds 
 
 Killed August L'3. Xo weight taken. 
 + 3 I 
 — 4 Died September 9. 
 
 3 Average loss 1.39 per cent. 
 
LOCOWEED DISEASE OF SHEEP 
 
 411 
 
 TABLK ^ Ill-Continued 
 B, cwr.s 
 
 TAG NO. 
 
 INITIAL PINAL 
 WEIGHT WEIGHT 
 
 ALTERA- 
 TION IN 1 REMARKS 
 WEIGHT 
 
 74 
 
 69 
 68 
 66 
 72 
 
 79 ' 79 
 
 108 97 
 74 72 
 110 102 
 
 78 : 77 
 
 ! 
 
 
 
 - 11 
 
 — s 
 
 - > 1 
 
 Total 
 
 449 j 427 
 
 - 22 1 Avcrafie lows 4.9 per cent. 
 
 C, lambs 
 
 59 
 
 22 
 
 23 
 
 + 1 
 
 Died September 6, weijiht of 20pound.s. 
 
 46 
 
 41 
 
 37 
 
 - 4 
 
 Died August 29. 
 
 49 
 
 ! 30 
 
 31 
 
 + 1 
 
 
 56 
 
 31 
 
 32 
 
 + 1 
 
 
 58 
 
 i 25 
 
 23 
 
 - 2 
 
 Killed August 19. 
 
 Total 
 
 . 149 
 
 146 
 
 - 3 
 
 Average loss 2.01 per cent. 
 
 Total initial weight of all animals in Group VII (ex- 
 cluding Xo. 25) 814 pounds 
 
 Total final weight of all animals in (iroup ^TI (exchid- 
 
 ing No. 25) 786 pounds 
 
 Total lo^s of weight of all animals in Group VII 28 pounds 
 
 Average alteration of all animals in Ciroup VII 3.43 per cent decrease 
 
 Group VIII, receiving no alfalfa and no salt; fed on locoweed, etc. 
 
 T.VBLE IX 
 
 A, yearlings 
 
 TAG NO. 
 
 INITIAL 
 WEIGHT 
 
 FINAL 
 WEIGHT 
 
 ALTERA- 
 TION IN 
 WEIGHT 
 
 
 REMARKS 
 
 
 pounds 
 
 pounds 
 
 1 pounds 
 
 
 
 13 
 
 77 
 
 78 
 
 ' + 1 
 
 
 
 30 
 
 74 
 
 72 
 
 i - - 
 
 
 
 28 
 
 "1 
 
 70 
 
 1 - ^ 
 
 
 ■ 
 
 7 
 
 70 
 
 71 
 
 - 1 
 
 
 
 Total 
 
 292 
 
 291 
 
 Average 
 
 loss 0.34 per cent. 
 
412 
 
 UNIVERSITi' OF VIRGINIA PUBLICATION^ 
 
 TABLE IX— Continued 
 
 
 
 
 B, t 
 
 wes 
 
 TAG NO. 
 
 INITIAL 
 WEIGHT 
 
 FINAL 
 WEIGHT 
 
 ALTERA- 
 TION IN 
 WEIGHT 
 
 1 REMARKS 
 
 81 
 
 72 
 
 70 
 
 _ 2 
 
 1 
 
 82 
 
 (76) 
 
 
 
 Died. Weight not recorded. 
 
 77 
 
 69 
 
 64 
 
 — 5 
 
 
 79 
 
 74 
 
 84 
 
 + 10 
 
 , 
 
 83 
 
 72 
 
 79 
 
 + 7 
 
 I 
 
 Total 
 
 287 
 
 297 
 
 + 10 
 
 Average gain 3.48 per cent 
 
 
 
 
 C, lambs 
 
 57 
 
 37 
 
 37 
 
 
 
 
 47 
 
 22 
 
 15 
 
 - 7 
 
 Died August 21. 
 
 54 
 
 31 
 
 34 
 
 + 3 1 
 
 60 
 
 30 
 
 33 
 
 + 3 
 
 
 50 
 
 29 
 
 22 
 
 - 7 
 
 Died August 29. 
 
 Total 
 
 149 
 
 141 
 
 - 8 
 
 Average loss 5.67 per cent. 
 
 Total initial weight of Group VIII (excluding 
 
 No. 82) 728 pounds 
 
 Total final weight of Group \lll (excluding No. 
 
 82) 729 pounds 
 
 Total alteration in weight of Group VIII 1 pound gain 
 
 Average alteration in weight of Group VIII 0.0137 per cent increase 
 
 A study of these tables corrobonites the general impressions derived 
 from daily inspections of the experimental animals, and justifies the fol- 
 lowing conclusions. 
 
 1. The animals were not particularly large, the gains in weight were 
 small even at the best. 
 
 2. The animals which increased most in weight were those in Groups 
 IV and V (receiving alfalfa and locoweed, Tables V and VI), their gains 
 being far ahead of those made by any other animals used in the experiment. 
 The animals in Groups I and II (Tables II and III, alfalfa but no locoweed), 
 came next, but they did not gain nearly so much. The animals in Group 
 III (Table IV, one-half alfalfa, no loco) and Group VI (Table VII, one-half 
 alfalfa, and locoweed) were third, with gains which were nearly the same 
 in each group. As might be expected, groups VII and VIII (Tables VIII 
 and IX, no alfalfa, all locoweed), made the worst showing, and presented a 
 total actual loss of weight. 
 
LOrOWEED DISEASE OF SHEEP 413 
 
 3. The animals receiving half rations of alfalfa, and locoweed (Table 
 VII — A, Group VI) throve better than those on half rations not eating 
 locoweed (Group III, Table IV). 
 
 4. The gains in weight were directly proportional to the actual amount 
 of food and also to the amount of fresh forage obtained by the sheep. 
 
 5. The animals which throve best were eating abundantly of locoweed, 
 in addition to having an abundance of alfalfa hay together with the rather 
 scanty natural forage of growing plants other than locoweed. 
 
 6. Animals receiving no salt (Group II, Table HI and Group V, Table 
 VI) , gained more in weight than the animals receiving salt (Groups I and IV) . 
 The unsalted animals on locoweed alone (Group VIII, Table IX) gained 
 1 lb., while the salted animals on loco alone (Group VII) lost 28 lbs. It 
 is remarkable that the lambs on locoweed with no salt (Table IX, C) lost 
 more weight than the lambs on locoweed with salt, (Table VIII, C) while 
 with the yearlings on locoweed (Tables IX, A and Table VIII, A), and es- 
 pecially with the ewes (Tables IX, B and VIII, B), the unsalted were better 
 off. Although slightly heavier, the unsalted animals were not more resis- 
 tant to the sheep fly disease. 
 
 7. In general, the larger and stronger animals did better in each corral 
 than the younger and weaker ones ; (seen by comparing the average altera- 
 tion in weight of the ewes, yearlings and lambs, respectively, in Groups 
 VII and VIII, and remembering that the greatest relative increase should 
 be found in growing lambs). 
 
 8. The tables show clearly that when enough nutritious food is pro- 
 vided, the locoweed (A. spicatus) certainly does not injure the health of 
 sheep, within the limits of time taken for this experiment. 
 
 In addition to the inductions just drawn from the tables, the general 
 conclusions from the experiment may be stated in brief; 
 
 1. Healthy sheep appear not to eat locoweed if thej^ can easily ol)tain 
 a plentiful supply of green forage. 
 
 2. Sheep can easily be made to eat locoweed b}^ depriving them of other 
 food; by diminishing other food; or by diminishing other green forage 
 available, even though the animals be well fed on alfalfa. 
 
 3. Animals which have started to eat locoweed, do not eat it to the ex- 
 clusion of other food, although they do appear to eat rather more of loco- 
 weed than of any other single plant. The lambs eat the leaves, the year- 
 lings and adult sheep eat the stalks and pods. Once in a while an adult 
 sheep will be found rubbing with his forefeet for the root of the weed, but 
 this was rare. The usual cause for sheep rubbing the nose in the ground is 
 the presence of sheep fly larvae in the nose. 
 
414 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 4. There was no evidence that the locoweed produced any poisonous 
 effect, clinical or anatomical, in a single sheep during the fifty-three days of 
 this experiment. The evidence indicates that the food value of the weed 
 must be very slight, but if the plant has any narcotic or other action, it is 
 so obscure that it could not be made out by careful and frequent observa- 
 tions of the animals used for this experiment. It is to be noted again that 
 no symptoms developed when the sheep eating the plant were suddenly 
 deprived of it, nor when they were returned to it after a week's abstinence; 
 and that sheep on abundant locoweed and abundant other food were the 
 ones which throve better than any others in this experiment. 
 
 5. The sheep used in this experiment did not thrive. This applies to 
 the sheep receiving alfalfa only, as well as to those receiving loco. At the 
 beginning of the experiment the sheep and lambs were average healthy 
 specimens. At the end of the experiment the animals had either gained 
 very little or had lost weight and were evidently in much poorer shape than 
 the members of the flock from which they were selected and which had been 
 kept on the mountain side. The causes for the failure of these sheep to 
 do well were probably confinement, lack of protection against the intense 
 heat of the sun, insufficient green forage, and inadequacy of food in the case 
 of those not receiving alfalfa. 
 
 6. During the course of the experiment, sheep fly disease broke out 
 among the animals, giving every appearance popularly attributed to loco 
 disease, and affecting indifferently those eating locoweed and those not 
 eating it. The animals most severely diseased were those receiving the 
 least food. 
 
 7. The vermifuges used before starting the experiment did not remove 
 the Thysanosoma actinioides. 
 
 8. In the course of this rather short experiment, no ill effects were ob- 
 served in animals deprived of salt. 
 
 Soon after concluding the feeding experiment at Ten Mile Flat, the 
 sheep which remained were sent to the Montana Agricultural College 
 where interesting studies were made to determine whether they could be 
 profitably fattened for market. The report of the experiment has been pub- 
 lished by Linfield (Bull. No. 59, Montana Agricult. Exp. Sta., 1905). He 
 found that the sheep gained only about half as fast as healthy sheep, and 
 that it was unprofitable to prepare them for market on account of the 
 length of time and cost of the feed required to fatten them. 
 
 From time to time during the experiment, a yearling or a lamb died, or 
 was killed, and examined at autopsy. The sheep fly larvae were found in 
 great abundance wandering over the nasal passages and up into the cavi- 
 
LOCO WEED DISEASE OF SHEEP 415 
 
 ties of the head; bronchopneumonia and parasitic worms were also found. 
 A few typical autopsies are detailed below, and the others are summarized. 
 
 Autopsy 16. Lamb No. 52, from Corral VI, May lamb of Van Cleve's flock, weight 
 18 pounds, length 28? inches from tip of nose to root of tail. Lamb had been in poor 
 condition for some time, suffering with cough, like the rest of the flock, frequently 
 digging its nose into the ground, and occasionally raising its head high in the air. 
 The animal was very weak, walked feebly, ran behind the rest of the bunch of sheep, 
 raising its legs, especially the hind legs, as if wading through water. On August 6 the 
 animal looked very ill, the cough and running from the eyes being very pronounced, 
 the face being swollen and the animal very weak. The lamb died on the evening of 
 August 7 and was autopsied at 9.30 a.m., August 8. 
 
 Anatomical diagnosis. Acute bronchopneumonia right and left lungs, with 
 abscess formation, empyema, and bronchitis; acute intense inflammation of mucous 
 membranes of nasal passages and superior orbital sinuses; twenty to forty embryos 
 of Oestrus avis crawling in sinuses, nares and trachea. Emaciation. Adhesions be- 
 tween omentum, ventral wall, intestines and stomach with cysts in the midst of the 
 adhesions containing caseous-purulent contents {Cijsticercus tenuicollis?) ; openings 
 from the paunch into four of above-mentioned cysts. Sarcosporidiosis. Irregular in- 
 cisor teeth. 
 
 The lamb was undersized with practically no subcutaneous fat, muscle reddish 
 brown, clear and translucent. Several lymph glands in the femoral region were found 
 large, red and soft; on section being much injected, and having dilated capillaries. 
 The abdominal wall was tightly adherent to the omentum by fibrous adhesions which 
 also bound the omentum to the paunch and intestines. In the adhesions were twenty 
 or thirty small cysts about 1 x § cm. with walls appro-ximately 1 or 2 mm. thick. 
 These cysts were smooth on the inside but exteriorly were bound in fibrous tissue. 
 One cyst contained a formless mass of semi-caseous, yellow, purulent material. The 
 cysts were distributed on the under surface of the diaphragm, over the paunch, in 
 the loops of the gut and in the pelvis. The omentum and mesentery were devoid of 
 fat. Mesenteric and retroperitoneal lymph glands large and soft, the retroperi- 
 toneal lymph glands were numerous, varying in size from a pin's head to 3 mm. in 
 diameter. The intestines were clear throughout, the stomach contained a moderate 
 amount of soft food. In the first stomach opposite the transverse furrow were three 
 or four round openings 4 or 5 mm. in diameter extending through the stomach wall 
 and communicating directly with the cavity of the caseous cyst described above, 
 pressure upon the cysts forcing pus through the stomach openings. 
 
 Spleen 10 x 6§ x 2 cm., small, soft, no adhesions. On section very soft, structures 
 not visible. Liver of fair size, surface smooth. The gall bladder and bile ducts were 
 clear. Kidneys; capsule stripped readily, leaving pale mottled surface with the cor- 
 tex averaging 11 mm. On section the kidney was gray, and cloudy, the glomeruli 
 were seen indistinctly, the striations easily visible. The pelvic organs and adrenals 
 were normal, the pancreas was soft and showed post-mortem changes. 
 
 Thorax. The left lung was tightly bound by fibrous adhesions to the chest wall, 
 the apex and dorsal surface of the lung being free, the rest of it being bound to the 
 chest wall, to the pericardium and the diaphragm. In freeing the lung a cavity was 
 opened into in the lower left lobe and about 100 cc. of thick yellowish gray pus escaped. 
 The entire lung was consolidated except the apex and upper dorsal part of upper lobe. 
 
416 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 The cavity occupied two-thirds of the lower lobe on the ventral and inferior sides. 
 On section the cavity had smooth lining and contained pus and semi-caseous yellow- 
 ish material. The consolidated lung was of a dark red color, not crepitant, rather 
 dry with very little excess of mucus in the bronchi. The bronchi were injected, the 
 bronchial lymph glands greatly enlarged, red and soft. The right lung was also adher- 
 ent to the diaphragm and pericardium and to the ventral surface of chest wall. There 
 were several abscesses varying from 5 to 8 cm. in diameter in the lower lobe, the 
 consolidated portions resembling the left lung. 
 
 Heart. The pericardial and epicardial fat was absent. The surfaces were smooth 
 and glistening. On the anterior (ventral) surface were a few ecchymoses. The 
 valves were clear and delicate, the endocardium clear, the myocardium pale grayish 
 brown, opaque. Just below the larnyx several Oestrus larvae were found crawling 
 around the trachea, which wal markedly injected. The mouth was clear, the incisor 
 teeth were loose and twice as long as normal. Nares. The nose was covered with 
 mud. On longitudinal section of the head the mucous membrane over the turbinated 
 bones, septum, etc., was intensely engorged, dark red in color, ecchymotic and covered 
 with thick nuico-pus. Great numbers of small Oestrus larvae were found crawling 
 over the mucous membranes as high as the ethmoidal turbinates. Brain and spinal 
 cord presented no abnormality. 
 
 Microscopw report. The heart cells were granular, the cross striations not dis- 
 tinct. Nosarcocysts were found. Lung. Sections from several parts of lungs showed 
 areas of bronchopneumonia with abscess formation. The pleura was considerably 
 thickened, showing granulation tissue together with large pink mononucleated cells, 
 lymphocytes and polymorphonuclear leukocytes. In a section through the edge of 
 an abscess, the necrotic tissue in the center presented the appearance of a homoge- 
 neous debris; passing out from the center there were zones of inflammation becoming 
 less intense to almost normal lung tissue. In the zones of inflammation the predomi- 
 nating cells were large, mononucleated cells with bright pink granular cytoplasm, 
 together with numerous lymphocytes and polymorphonuclear leukocytes. The 
 distribution of the exudate in the lung alveoli was irregular, some alveoli being 
 plugged with exudate, others empty. Desquamated cells and debris appeared in 
 the lumina of the bronchi. Spleen, capsule not thickened, malpighian bodies visible 
 but not conspicuous, showing evidence of hyperplasia in the centers; the pulp con- 
 gested, it being difficult to distinguish sinuses from pulp. In the pulp were found 
 many red cells and fragments of red cells together with large endothelioid cells which 
 frequently were more or less tinged with blood pigment. A few cells resembling 
 nucleated reds but not positively identifiable were seen in the pulp. Liver, the cells 
 and cell columns were separated, the cells being swollen and vacuolated as if from 
 post-mortem change. Kidney, the epithelium lining the tubules was extremely gran- 
 ular, cloudy and rather vacuolated. Lymph gland, capsule appeared rather edema- 
 tous, the peripheral sinus only faintly seen. Cell nests not separated from cell col- 
 umns. The striking feature of the lymph gland was that the peripherj^ of the gland 
 was densely packed with lymphoid cells while the central portions were especially 
 marked by dilated sinuses partly filled with what appeared to be free cells. The cells 
 in the peripheral region varied from small lymphoid cells to large mononuclears, the 
 former predominating. Some of the larger cells had a bright pink non-granular 
 cytoplasm. The dilated sinuses were moderately well filled with large desquamated 
 endothelial cells with vacuolated or pink cytoplasm together with fairly abundant 
 
LOCOWEED DISEASE OF SHEEP 417 
 
 lymphoid cells. The desquamated endothelial cells dominated the appearance in the 
 sinuses. The blood vessels of the lymph gland were niarkedl}^ congested. 
 
 Voluntary muscle. Poorly preserved, showed .small bodies which were not very 
 distinct but appeared to be sarcosporidia. 
 
 Section through abscess cyst of omentum. Cyst was about 1 cm. .\ i. Capsule 
 thin, the outer part being made of laminated connective tissue, the inner portion 
 of young granulation tissue in which there were great numbers of cells resembling 
 large mononuclear leukocytes, and a number of small mononuclears, together with 
 many rather graimlar and swollen cells of fibroblastic appearance. The inner edge of 
 the wall passed off suddenly into a region of coagulation necrosis in which were found 
 fragmenting nuclei, polymorphonuclear leukocytes and purple debris. This was 
 continuous with a pinkish granular debris filling the center of the cavity. There was 
 no evidence of daughter tubercle formation in the wall of the cyst but the general 
 appearance suggested tuberculosis as a possible diagnosis. 
 
 Autopsy 17. Lamb 58, from Corral VII (no alfalfa), had become very ill but had im- 
 proved markedly when fed on alfalfa, when the experiment was interrupted, and had 
 remained fairly well after being returned to the loco diet; was removed from the corral 
 for the examination. The temperature of the lamb was 101 (rectal temperature) ; the 
 lamb was emaciated and stiff-legged but was not one of the illest lambs in the corral. 
 It coughed a good deal but seemed in better condition than it had been previous to 
 the diet of alfalfa hay. Its weight was twenty-three pounds. The animal was chloro- 
 formed and autopsied at once on August 19. 
 
 Anatomical diagnosis. Oestrus ovis infection of nasal passages with muco-puru- 
 lent inflammation. Multiple pin head bronchopneumonic patches in both lungs. 
 Emaciation. Infarction in liver; Thysnnosoma actinioides hepatitis. Irregular in- 
 cisor teeth. 
 
 The skin, muscles, and peritoneal cavity were clear; there was a small amount of 
 fat. The spleen was. small, soft, translucent, the structures appearing normal. The 
 liver was smooth, semi-translucent excepting for an irregular wedge-shaped area on 
 the upper surface on the left lobe just to the left of midline. This area was not raised, 
 was smooth and had a mottled, grayish red color with fine, pin point dark mottlings. 
 On section the area was wedge-shaped extending U cm. into the liver. The kidneys, 
 pancreas, and bile ducts, stomachs, pelvic viscera, and adrenals presented no ab- 
 normalit^y. One small, fringed tapeworm found in the intestines. Heart contained 
 a fair amomit of fat; was clear throughout except tluit muscle was rather gray and 
 opaque. 
 
 The lungs were voluminous, surface smooth, for the most part pink, but mottled 
 at irregular intervals with dark red points varying from a pin head to 1 cm. in size. 
 On section the dotted appearance was also seen as if from very numerous, small 
 areas of consolidation. There were no tubercles and no cavities found. The right 
 and left lung were alike. The bronchi and trachea contained frothy, blood-tinged 
 mucus. The turbinated passages were swollen, dark red and covered with muco-pus. 
 A large Oestrus larvae and six small ones were found in the nasal passages. The in- 
 cisor teeth were unusually long. 
 
 Microscopic report. Heart striations and hbrillations distinct, often the clear 
 space around the heart nucleus seemed rather larger than usual. No other noticeable 
 alteration. Lung, showed small regions in which the alveoli were packed with red 
 cells and coagulated albumin, alternating with relativ(>ly normal lung. In tlie region 
 
418 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 with exudate there were remarkably few leukocytes and only a few desquamated 
 epithelial cells. No fibrin was made out in the H. and E. specimen. The bronchi were 
 practically clear. The alveolar capillaries in general congested. Spleen, malpighian 
 bodies conspicuous, rather dense, and larger than usual, apparently however, a nor- 
 mal spleen. 
 
 Liver. A small block showed considerable thickening throughout the portal 
 systems, chiefly around the bile ducts with rather edematous tissue. The central 
 third of the section was devoid of liver tissue and showed a mass of cellular material 
 with two or three areas of necrosis. In this tissue were dilated bile ducts. The cel- 
 lular tissue was composed of fibroblasts of various size, many of which contained a 
 slight amount of brownish pigment. Among them were mononuclears, pol3^morpho- 
 nuclears and eosinophiles. The eosinophiles were abundant and in part appeared 
 to have polymorphous nuclei, in other less frequent instances, single, round nuclei. 
 Compressed and degenerating liver tissue was found at the edge of this cellular ac- 
 cumulation and evidence of the extension into the liver of the newly forming connec- 
 tive tissue was met with. At the edge of the connective tissue there was hemorrhage 
 into the liver. Elsewhere the liver cells were cloudy, vacuolated and granular. 
 
 Kidney showed a moderate amount of coagulated albumin in the tubules. The 
 convoluted tubular epithelium moderately cloudy, otherwise the kidney appeared 
 normal. Mucosa of nares; the most striking feature was the very great dilatation 
 of the blood sinuses and bood vessels, the intervening tissue being distinctly edema- 
 tous. In the edematous tissue were found numerous eosinophiles with polymorphous 
 nuclei, large mononuclears and a few lymphocytes. The eosinophile was the most 
 striking and probably the most abundant infiltrating cell. The epithelium of the 
 glands was ver}^ cloudy and full of mucus. Immediately beneath the surface epithe- 
 lium there were rather dense accumulations of mononuclears, chiefly lymphocytes, 
 the eosinophiles beibg less abundant in this region. Section of lymph gland, showed 
 widely dilated central sinuses with phagocytic endothelial cells. Voluntary muscle 
 appeared clear, no sarcocysts being found. • Epithelium and wall of esophagus ap- 
 peared normal. 
 
 Axdopsy 18. Lamb 47 from Corral VIII. The lamb had been very feeble but had 
 improved during the week of alfalfa feedings. Subsequently it fell into worse con- 
 dition and died on the evening of August 21. The autopsy was performed at 2 p.m., 
 August 22. 
 
 Anatomical diagnosis. Oestrus avis infection; acute mucopurulent inflammation 
 of mucous membrane lining the nasal passages and accessory sinuses; bronchopneu- 
 monia with abscess formation. Infection with Thysanosoma actinioides . Irregular 
 incisor teeth. 
 
 The animal weighed 15 pounds, its wool was ragged, incisor teeth loose and long. 
 Emaciation was extreme. The peritoneal cavity was clear, there was no fat visible, 
 the mesenteric glands were large, pale and soft. 
 
 The liver, spleen and kidneys appeared normal. A small fringed tapeworm was 
 found in the small intestine. The stomachs appeared normal. Both lungs were ad- 
 herent over the ventral and oephalad portions by fibrous adhesions, denser on the 
 right side. In each lung were multiple small areas of consolidation with abscess 
 formation. The bronchi contained bloody mucus. Heart appeared normal, except 
 for absence of fat. On opening the head the engorgement of the mucous membrane of 
 the nasal passages was intense, there being many larvae crawling over the mucous 
 membrane with muco-pus and pin point hemorrhages into the mucosa. 
 
LOCOWEED DISEASE OF SHEEP 419 
 
 Microscopic report. Heart muscle cloudy, striations indistinct, fibrillations still 
 well marked. 
 
 Lung, showed bronchopneumonia, many of the alveoli being packed with a cel- 
 lular exudate, while adjacent alveoli were relatively free or showed only coagulated 
 albumin and desquamated epithelium. The exudate consisted of desquamated epi- 
 thelium, coagulated albumin and great numbers of polymorphonuclear cells. In 
 one or two of the alveoli elongated cells were met with of a fibroblast appearance but 
 new capillaries could not be seen. Section did not pass through one of the abscesses. 
 Spleen, capsule not thickened, malpighian bodies not very sharply marked but could 
 be seen. Pulp cellular, the sinuses not being distinct. Liver cells rather. large and 
 cloudy, being separated as if there was slight post mortem change, otherwise liver 
 seemed normal. Kidney, normal except for quite marked post mortem change af- 
 fecting the convoluted tubules. Parotid gland markedly congested, the acini being 
 made up of large purple mucus-containing cells which were not very well preserved. 
 Xo abnormality could be made out. Lymph gland presented much the features de- 
 scribed in previous autopsies, the periphery being packed with lymphoid cells, the 
 blood vessels intensely congested, the central sinuses widely dilated and containing 
 moderate numbers of free cells. Section through esophagus showed normal epithelium 
 and normal muscle wall. Section through vomer showed markedly dilated blood 
 vessels in the mucosa, with advanced mucoid change in the glands. There was also 
 edema of the tissue between the glands. Rather numerous and small lymphoid 
 cells were distributed throughout the mucosa. Section through turbinated bone; 
 the high columnar mucosa was fairly well preserved, beneath which came a markedly 
 edematous tissue containing greatly dilated blood vessels, eosinophiles, lymphoid 
 cells and large mononuclears. Sections through several regions of the nasal mucosa 
 showed similar conditions. In some regions the exudate was slightly more abundant 
 than in others, but the same general features prevailed. The glands in this tissue 
 usually contained a purplish material apparently mucus, sometimes a coagulated 
 pinkish material like albumin. 
 
 Autopsy 19. One of the yearlings from Corral VIII had looked rather ill for some 
 time but evidently was convalescing after the use of the alfalfa hay. The animal was 
 still coughing and sneezing; walked stiffly and had a bloody discharge from the nose. 
 On August 23, the animal was chloroformed and autopsied at once. 
 
 Anatomical diagnosis. Oestrus ovis infection, subacute. Ostertagia rnarshalli in 
 stomach; Thysanosoma actinioides in bile ducts, hepatitis, emaciation. Sarcospo- 
 ridiosis. 
 
 Autopsy 22. Lamb No. 48 was brought from Corral VI, in dying condition. It 
 was seen living on the morning of August 26, but was dead at 2 p.m. and was autop- 
 sied at once. 
 
 Anatomical diagnosis. Acute Oestrus oris infection. Acute bronchopneumonia. 
 Emaciation. 
 
 Autopsy 25. After two months of drouth a heavy cold rain. fell on the evening 
 of August 28. On the following morning lambs 46 from group VII, and 50 from 
 group VIII, were dead. Lamb 46 had always been a heavy feeder and looked like 
 one of the strongest in the pen. Autopsy, 8.15 a.m. 
 
 Anatomical diagnosis. Acute bronchopneumonia. Acute splenic tumor. Cloudy 
 swelling of myocardium, liver and kidney. Acute catarrhal enteritis of lower ileum 
 and cecum. Acute mucopurulent rhinitis and sinusitis with about a dozen young 
 
420 L-NIVEPSITV OF VIRGINIA PUBLICATIONS 
 
 Oestrus larvae and one or two older ones in the supraorbital sinus. Cysticercus lenui- 
 collis in peritoneal cavity. Sarcosporidiosis. Acute lymphadenitis. Brain and 
 spinal cord normal. 
 
 Autopsy 26. Lamb 50, Corral VIII, found dead on morning of August 29, after a 
 cold rain during the previous night. 
 
 Anatomical diagnosis. Acute bi-onchopnevunonia. Acute Oestrus avis rhinitis, 
 emaciation. Irregular incisor teeth. Brain normal. 
 
 Autopsy No. 30. Lamb No. 55, from Corral VI, was much stunted and emaciated. 
 Fleece was fairly regular and thick. The animal was very weak and uncertain on its 
 feet and walked with a stiff-legged gait. There was marked coughing and sneezing. 
 The respirations were difficult, irregular with many pauses and many short, broken, 
 inspirations. Taking the average of five minutes' count there were 100 respirations 
 per minute. The rectal temperature was 102°. The eyes were gummed with mucus. 
 The eyelids puffy and swollen. The nose was covered with muco-pus and dirt. The 
 lamb was so weak that it could hardly get to its feet when it had been laid on the 
 ground. September 1, 1904, animal was bled to death and autopsied at once. 
 
 Anatomical diagnosis. Subacute (convalescent) Oestrus rhinitis and sinusitis 
 with empyema of ethmoidal sinus, cervical lymphadenitis. Bronchopneumonia. 
 Emaciation. Irregular incisor teeth. Red marrow. Brain and spinal cord normal. 
 
 Lamb 53, from Corral VI, was selected for examination on September 1. The 
 hemogoblin was 70 per cent (Tallquist), the weight 26 pounds. The lamb was kept 
 till September 5 on alfalfa hay when the weight was 28^ pounds. Respirations were 
 irregular, 46 to the minute, temperature 102°. The paunch of the lamb was distinctly 
 distended; the animal was very weak and thin. When laid on the ground it could 
 hardly recover its feet. It walked with an uncertain stiff-legged gait. The animal at 
 time of examination on September 5 was in better condition than it was a week 
 earlier and for the last four days, between September 1 and 5 improved steadily 
 upon a hay diet. The animal had good vision, it recognized a person bringing 
 alfalfa or water to it. There was no evidence of psychic disturbance. The ani- 
 mal's breathing was distinctly impaired, especially at night and during early morn- 
 ing hours. In the morning, especially, the head was stuffed up, the eyelids being 
 gummed together and there being a discharge from the nose of thick mucus. The 
 animal was bled to death on September 5 and autopsietl at once. 
 
 Autopsy 31. Septembers, 904. 
 
 Anatomical diagnosis. Subsiding Oestrus rhinitis and sinusitis; empyema of 
 ethmoidal cells; bronchopneumonia; Thysanosoma actinioides dilating common duct, 
 cystic duct and beginning to enter liver ducts; Cysticercus tenuicollis; emaciation. 
 Irregular incisor teeth. Brain and cord, and stomachs and intestines normal. 
 
 Lamb No. 59 from corral VII was found dying on morning of September 6. Died 
 about 11 a.m. Autopsy at 1.30 p.m. 
 
 Autopsy 32. Anatomical diagnosis. Bronchopneimionia, serofibrinous pleurisy 
 on right and left; small purulent cysts in lungs. Oestrus ovis in nasal cavities; em- 
 pyema of ethmoidal turbinatea; Thysanosoma actinioides; emaciation. Acute splenic 
 tumor. Necrosis in lymph gland. 
 
LOCOWEED DISEASE OF SHEEP 421 
 
 D. DISCUSSION OF PARASITIC DISEASES ENCOUNTERED. 
 
 During the summers of 1903 and 1904 thirty-two autopsies were per- 
 formed; twenty-eight are included in the preceding report, one other was 
 upon an experimental' 'locoed" sheep at White Sulphur, Montana; three au- 
 topsies upon cattle have been discarded as they were performed hurriedly 
 and were unsatisfactory. In the twenty-nine autopsies on sheep the prin- 
 cipal diseases and parasites observed were: 
 
 TABLE X 
 
 Times 
 
 Thysanosoma actinioides, Total 29 
 
 Thysanosoma with peribiliary hepatitis 14 
 
 Thysanosoma with an abscess or infarction of liver .2 
 
 Stomach worms (Ostertagia marshalli) 8 
 
 Other intestinal worms 5 
 
 Lung worms 3 
 
 Oestrus ovis larvae 15 
 
 Sarcocystis tenella 15 
 
 Pneumonia, Total 18 
 
 Pneumonia, with lung worms 1 
 
 Pneumonia, with bronchiectatic abscesses, or cysts 4 
 
 Pneumonia, with oestrus ovis 15 
 
 Pneumonia, of unknown origin 3 
 
 Pneumonia, with pleurisy or empyema 2 
 
 Acute enteritis 1 
 
 Cysticercus tenuicoUis in peritoneal cavity 8 
 
 Cysticercus in pericardial cavity 1 
 
 Abscess, supposedly around cysticercus, total 5 
 
 Abscess, on epicardial surface 2 
 
 Abscess, on liver 1 
 
 Abscess, in peritoneal cavity 2 
 
 Hair balls in stomach 2 
 
 Renal calculi 2 
 
 Extradural abscess 1 
 
 Necrosis in lymph gland 1 
 
 Inflammatory nodule in kidney 1 
 
 Irregular incisor teeth* 14 
 
 Emaciation 16 
 
 * No note upon the teeth was made in other autopsies. 
 
 The Thysanosoma adinioides, or Taenia fimhriata, or "fringed tape- 
 worm" has attracted attention in this country chiefly from Curtice, (4th 
 and 5th Annual Reports, Bureau of Animal Industry, 1887-1888; pp. 167,- 
 186; also "The Animal Parasites of Sheep," Washington, 1890; also Vet. 
 
422 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 Record 1, p. 59J. He found that the smallest worms appeared in lambs of 
 about two months age, and occurred in sheep of all ages, and at all seasons 
 except possibly during the winter months. He was unable to remove the 
 parasite by treatment. He concluded that disease resulting from infection 
 with this parasite was commonly called "loco" disease, and he was scepti- 
 cal regarding the existence of true loco weed poisoning in sheep. He esti- 
 mated that the losses from death of sheep and depreciation due to this 
 parasite, were enormous, lambs and yearlings suffering chiefly. Practically 
 all Western flocks seemed to be infected but it seemed to be especially com- 
 mon among the descendents of the Mexican or Spanish sheep with which 
 the larger ranches were originally stocked. In all, he found 89 per cent of 
 Western sheep infected. 
 
 He saw the worms in the duodenum and bile ducts, the ducts being so 
 tightly distended with them at times that the worms could not be extracted 
 except in pieces. He also saw the worms in the pancreatic ducts. Thick- 
 ened and dilated ducts were found occasionally with no worms in them. 
 The chief features of the disease produced by the worms were those of pro- 
 gressing malnutrition, or cachexia, with occasional excess of fluid in the 
 serous cavities. In fatal cases death usually was due to starvation, exposure, 
 or intercurrent disease. 
 
 My findings corroborate those of Curtice in certain respects and in addi- 
 tion I have been able to demonstrate a serious lesion of the liver, with the ap- 
 pearance of a necrotic, organizing area in the liver, resembling an infarction; 
 while in one case (No. 4), there was a f ungating liver abscess in connection 
 with an extensive hemorrhagic subdiaphragmatic abscess. In a number of 
 autopsies the microscopic studies demonstrated the presence of a process 
 of fibrosis, more or less advanced, proceeding from around the thickened 
 ducts and extending out into the liver substance. 
 
 In other words, these cases establish a new form of chronic inflammation 
 of the liver, a form distinct from liver fluke disease on the one hand and 
 from the inflammation resulting from gall stone obstruction on the other, for 
 here the tapeworm, Thysanosoma, is responsible for the disease. 
 
 It may also be remarked that vacuolar changes were present in the pan- 
 creatic cells in a case where the pancreatic duct was filled with the tape 
 worm. From the nature of my work it was impossible to determine the 
 clinical course of the disease, but it seemed clear that heavy infections were 
 freciuently associated with malnutrition or cachexia.* 
 
 * A description of the microscopic changes in the liver together with a demon- 
 stration of sections was given by me in an article read before the American Association 
 of Pathologists and Bacteriologists at Philadelphia in April, 1912. 
 
LOCOWEED DISEASE OF SHEEP 423 
 
 Oestrus ovis infection. Aside from the microscopic studies of the nasal 
 mucous membranes and cervical lymph glands, detailed in the autopsies at 
 the end of Section C, my studies emphasize only two points with regard to 
 Oestrus ovis infection; first, that this parasite is a source of danger to 
 Western sheep ; second, that the severity of the symptoms produced by the 
 parasite depends most intimately upon the general condition of the animal, 
 and upon the amount of nutritious food which it receives. 
 
 It is of interest to observe that the Sarcocystis tenella was present in 
 practically every case in which the microscopic examination was made ex- 
 cept in the case of lambs only 3 or 4 months old. It is, however, not gener- 
 ally regarded as a dangerous infectious agent, although according to J. 
 Fiebiger, {DietierischenParasitender Haus-und-Nutztiere; 1912, p. 113-119) 
 during one year 1| per cent of sheep at Budapest were condemned as unfit 
 for food on account of infection with this parasite. 
 
 No special remarks are required concerning the lung and stomach worms, 
 for parasites of this type are known the world over. It is to be noted how- 
 ever, that this report together with the recent work from the Bureau of 
 Animal Industry shows that the semi-arid condition of the general grazing 
 grounds in the West is no protection against the spread of several dangerous 
 parasites, when the bed grounds, watering places, etc., are allowed to 
 become polluted, and to remain so. 
 
 E. REVIEW OF RECENT PUBLICATIONS DEALING WITH LOCOWEED DISEASE. 
 
 The office of the Poisonous Plant Investigations in the Bureau of Plant 
 Industry continued the study of locoweed disease, after the conclusions 
 which I drew from the field work of 1903 and 1904 had been submitted. 
 A double-headed campaign was launched, in which Dr. Albert C. Craw- 
 ford iloc. cit.) conducted investigations designed to test the poisonous 
 action of the locoweed under laboratory conditions and to ascertain the 
 nature of the poisons obtained, while Dr. C. Dwight Marsh iloc. cit.) car- 
 ried out experimental studies of the loco problem in the field. 
 
 After a scholarly review of the literature, Crawford details his own 
 elaborate experiments, which led him to conclude that the symptoms of 
 loco poisoning can be reproduced in rabbits by feeding them extracts of 
 certain loco plants; that the symptoms in the rabbits which he studied 
 were due to the barium in the locoweed extract; that there may be other 
 poisonous principles in locoweeds from other regions, and that locoweed 
 grown on some soils contains no barium and is not active. 
 
 As Dr. Crawford did not test the locoweed grown in the region where 
 
424 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 my experiments were conducted, it cannot be determined, except by a 
 special study, whether he would have placed these particular locoweeds in 
 the barium-containing, actively poisonous group, or in his inactive group 
 free from barium. But this much is certain; the sheep which ate this loco- 
 weed freely for the greater part of the fifty-three days of the experiment 
 presented neither the symptoms, nor anatomical changes which Crawford 
 gives as characteristic of barium poisoning. A recent publication by Als- 
 berg and Black weakens the force of Crawford's conclusions. These writers, 
 (Bureau of Plant Industry, 1912, Bull. 246) as the result of experiments 
 and other considerations which they record, are led to the conviction that 
 the toxicity of locoweeds in laboratory experiments is not due to barium, 
 and Marsh also (Bull. 246) concludes from studies in the field that typical 
 loco poisoning is not produced by barium feeding alone. Up to the present 
 no further laboratory studies have been published, and it now looks as if 
 Crawford's view as to barium cannot be maintained, but that his experi- 
 ments at least suggest that some locoweeds contain a poison of unknown 
 nature which other locoweeds do not contain. 
 
 The second division of the attack upon the loco problem was under 
 the direction of Dr. Marsh who conducted feeding experiments upon a 
 larger and more thorough scale than had ever before been attempted. For 
 three seasons, 1905, 1906, and 1907, horses and cattle were fed upon loco- 
 weed in three camps established in Colorado and Nebraska. The animals 
 were observed during life, autopsies were performed on many of them, and 
 many other locoed animals, horses, cattle, sheep, and goats were examined. 
 Accounts of the experiments and of the results obtained appear in several 
 bulletins from the Department of Agriculture, and in reports from the Agri- 
 cultural Experimental Stations of Colorado and Nebraska which actively 
 cooperated in Marsh's work. From these accounts it is clear that Marsh be- 
 lieves that he has solved the loco problem, that he has proved that the 
 locoweed is poisonous, and that he has established symptoms and anatom- 
 ical changes which are together equally characteristic of locoweed intoxica- 
 tion. It is, however, difficult for a medical reader studying Marsh's reports 
 to follow him to his conclusions, for the data which he prints in his technical 
 report (Bull. 112), and elsewhere, do not always make it logically necessary 
 for the reader to come to the same conclusions that Marsh reached. This is 
 noticeable between pp. 47 and 72 in his review of cases, where it cannot be 
 seen by the reader that Marsh has always excluded other possible diagnoses 
 with sufficient fulness to justify his conclusions that the animals described 
 owed their maladies to the locoweed. This deficiency may be corrected 
 when he publishes in full his anatomic, microscopic, and bacteriologic stud- 
 
LocowEf:D diskasp: of sheep 425 
 
 ies, which references in Bulletin 112 allow us to expect. It is, however, 
 clear that Marsh's animals on locoweed diet became ill and died, while 
 controls, not eating locoweed remained healthy. The following analysis 
 of Marsh's publications represents an attempt to construct the clearest 
 possible medical description of Marsh's animals, and incidentally indicates 
 the variations which he mentions. Marsh, (Bureau Animal Industry, Bull. 
 112; 1909, p. 114) claims that "animals eating (the loco plants) succumb 
 sooner or later to their poisonous action." He modifies this statement 
 elsewhere; thus, (Farmer's Bull. 380, p. 10): 
 
 Dui"ing the spring months, before the grass starts, where the white locoweed is 
 abundant practically all animals eat more or less of it. As the grass becomes more 
 abundant, many of these leave the locoweeds and devote themselves entirely to grass. 
 These animals as a rule do not seem to be injured by the habit. Others .... 
 continue to eat the locoweed even where there is an abundance of other feed. 
 Whether an animal will become locoed or not is then simply a matter dependent upon 
 the individual. Some cattle and horses will eat locoweeds for a part of the year, for 
 a period of years and suffer no harm. Others .... cat this plant almost 
 exclusively, and these will die within a few months, or, in some cases, even within 
 a few weeks. 
 
 The same idea occurs also in Bulletin 112 (Case No. 10., etc.) 
 The symptoms were essentially like those popularly described, a stag- 
 gering, stiff, and uncertain gait, the hind legs being dragged frequently; a 
 general disturbance of the nervous system which leads in some cases to an 
 apparent partial paralysis of the limbs and to a very distinct lack of mus- 
 cular coordination. Anaesthesia of the skin may be pronounced. 
 
 "The animals eating loco eat more and more of it, although they do not in all 
 cases acquire a passionate love for the weed, and sooner or later lose flesh, and die of 
 starvation." .... "The first pronounced symptom (Bull. 246, p. 34) is in the 
 gait, which is stiff with more or less evidence of partial paralysis. There is a lack 
 of muscular coordination, which produces 'high stepping,' rearing, jumping and 
 stumbling." In drinking, the mouth moves in a peculiar way, somewhat as in eat- 
 ing. "The animal is either dull and dejected or in constant motion .... 
 It gradually loses flesh, its coat becomes rough, its eyes staring, it becomes pro- 
 foundly anemic, and eventually it dies of starvation." 
 
 Abortion is common among locoed cows. The temperature is usually 
 normal, but varies from subnormal to 108°F. Marsh's colleagues, Peters 
 and Sturdevant, from the Nebraska Agricultural Experiment Station (21st 
 Annual Report, 1908) add to these symptoms, that the horses experimented 
 with showed distinct irregular swellings more or less bilaterally sj^mmetrical, 
 which appeared early on the cheeks and side of the lower jaw as well as 
 "on the place behind the lower lip." Lymphatic enlargement in the inter- 
 
426 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 maxillary space also appeared early. Marsh found (p. 92) that "during 
 the early period of loco feeding there were no symptoms of poisoning. 
 Horses and cattle will eat quite freely of the weed for a considerable period 
 with no apparent ill effects and may even gain considerably in flesh." 
 Marsh frequently speaks of malnutrition among his animals, and of their 
 starving to death, but it is only very recently (Farmers Bulletin 536, is- 
 sued May 1, 1913), that he has begun to come around to the view expressed 
 in my reports of 1903 and 1905 that underfeeding is one of the main 
 causes of the loss of Western live stock. 
 
 Great individual differences were found to exist among animals in re- 
 gard to susceptibility to the loco poison; in general, the better bred animals 
 succumbed more quickly. Horses were the principal animals attacked in 
 regions where the Astragalus mollissimus prevailed. This was found much 
 more toxic than the Ai'agalus lamberti which did more damage to cattle 
 and sheep than to horses. 
 
 In most of his experimental animals the symptoms were of sudden onset. 
 The weed was eaten by the animal with no evidence of injury until a rela- 
 tively short time before death, when symptoms developed rapidly. The in- 
 terval from the time the animal began to eat locoweed until its death 
 varied from two months and eight days to six months and nine days; with 
 cattle the average interval was about five months, with horses rather less. 
 If the animal ate only moderate amounts of loco, a fatal outcome was in- 
 definitely delayed. Cases of "acute" locoism in lambs were met with in 
 which death resulted in two or three weeks from the first eating of the loco- 
 weed. Age was not a factor in the disease, old as well as young animals 
 becoming locoed. 
 
 Marsh states (p. 114), that there were certain quite definite anatomical 
 changes found at autopsy. 
 
 The animals were strongly anemic. This anemia was indicated not only by 
 paleness of flesh and actual loss of blood, but by serous deposits in various parts of 
 the body. The blood was found to be poor in hemoglobin and commonly rather rich 
 in leukocytes. 
 
 Elsewhere (p. 95) he says that the anemia 
 
 is indicated not only by the emaciation and paleness of the flesh, but by the 
 excess of serous fluids of the body and by the deposits of organized serum in various 
 parts of the body. This is more especially marked at the base of the ventricle of the 
 heart. 
 
 Elsewhere (Farmer's Bull. 380, p. 12) Marsh states: 
 
LOCOWEED DISEASE OF SHEEP 427 
 
 The postmortem examinations of locoed animals do not in all cases show clearly 
 marked evidence of the progress of the disease. Since in all cases of fatal poisoning 
 the locoed animals die of starvation they are profoundly anemic, as would be expected, 
 and, as a result of this anemia, accumulations of coagulated serum in gelatinous 
 form are found in various parts of the body. These accumulations are particularly 
 prominent about the heart. There is also an accumulation of coagulated serum in 
 the cavity of the spinal column. This is almost always present in cases where the 
 loco poisoning has become a chronic condition. 
 
 This remarkable condition in the spinal canal is described as follows by 
 Marsh in the section of his main work devoted to the antomical changes 
 
 (p. 97-98) : 
 
 The central nervous system is generally in a hyperemic or congested condition. 
 In a few cases clots were found in the lateral ventricles of the brain. We have never, 
 however, found clots in the fourth ventricle .... The serous exudate in the 
 epidural space is especially abundant, and is more or less organized. Commonly 
 it is particularly abundant about the points of exit of the spinal nerves. This condi- 
 tion is rarely absent in chronic locoes In some cases this coagulated 
 
 serimn is especially abundant in the lumbar region .... 
 
 Later (p. 114) he states that the fluid of the epidural space of the spinal 
 canal is rather unusually abundant, and commonly more or less organized, 
 "so that the spinal canal frequently seems to be filled with a jelly like sub- 
 stance." Peters and Sturdevant, Marsh's colleagues, describe as follows 
 the condition as it was met with in a seventeen months old horse which 
 died under loco treatment (21st Annual Report; Agricultural Experimental 
 Station of Nebraska, 1908). Between the dura mater and the periosteum 
 of the vertebrae enclosing the neural canal all along the spinal cord there 
 was a cherry red transparent organized exudate in great abundance. In 
 another horse the exudate varied from a buff color in the lumbar region 
 to a very dark red in the cervical region. The color of the exudate was due 
 to numerous tiny blood vessels running through in all directions. The ex- 
 udate "was not adherent to either periosteum or dura but clung to the 
 spinal nerves at their origin, since it ran through and filled the opening 
 between the anterior and posterior nerve roots in each case and was thus 
 held in place by these." 
 
 Marsh also autopsied five lambs which died of acute loco disease lasting 
 only two or three weeks (p. 71). All were in good flesh; "all had clots in the 
 lateral ventricles. All had serous coagulum in the spinal canal, and all 
 had congested walls of the fourth stomach. This would seem to confirm our 
 opinion that these lesions are characteristic of the locoed condition, but 
 that in chronic cases they may be more or less masked." There is some 
 
428 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 contradiction between this and his reiterated statements that these lesions, 
 especially the spinal canal lesions, are peculiarly characteristic of chronic, 
 not of acute, loco disease. Moreover, as these lambs were affected for only 
 two or three weeks, the anemia alone would hardly have progressed with 
 such rapidity as to cause the serous effusions, in the absence of some more 
 direct cause. From these accounts it appears that this peculiar 'coagu- 
 lum ' was sometimes outside the dura, 'epidural,' at other times in the 
 cavity of the spinal column. 
 
 Marsh found also changes in the stomach at autopsy- on locoed animals, 
 (p. 114) "A diseased condition of the stomach was a common accompani- 
 ment of the locoed condition, this being marked in cattle by ulcers in the 
 fourth stomach." In another place, (p. 97), he says: 
 
 In acute cases the (stomach) walls are very much inflamed. In chronic cases 
 ulcers are commonly present. The ulcers are not so common in the stomach of horses, 
 but are almost invariably present in the fourth stomachs of cattle. In sheep one is 
 apt to find inflamed walls rather than ulcers. In these ulcers a microscopic examina- 
 tion shows that the mucous membrane is entirely destroyed. Sometimes other 
 parts of the alimentary canal may be inflamed or have small ulcers but this is not a 
 usual condition. 
 
 In another place (Bull. 246, p. 34) he states, that, as the result of loco 
 feeding, ulcers are found in the stomachs of horses and in the fourth stom- 
 achs of cattle and sheep. In addition Marsh found that the hemolymph 
 glands were unduly prominent and very numerous, and ovarian disease 
 was common. 
 
 The picture was not uniform in all of Marsh's experimental animals. 
 Two horses developed acute glanders (p. 461). Others, according to 
 Glover, Marsh's colleague (Colorado Agricultural Experiment Station, 
 18th Annual Report, p. 52), showed unmistakable symptoms of starvation, 
 and on careful autopsy, revealed no characteristic lesion. 
 
 Marsh laj^s great emphasis upon the anemia observed in locoed animals. 
 He found no blood parasites upon examination (p. 92). He found it im- 
 possible, however, on account of other duties to secure any very large 
 number of blood determinations. Some counts were made during the sec- 
 ond and third summers. The normal number of red corpuscles for healthy 
 cattle was found to be something over 8,000,000. The count was high, as 
 the experiment camp was at an altitude of 5,000 feet above the sea. The 
 hemoglobin (Tallquist) , averaged between 90 and 95 per cent. Very severely 
 locoed animals in the last stages of the disease, examined in 1906 gave an 
 average of over 5,000,000 corpuscles, with hemoglobin averaging 70 per 
 cent, while convalescents and those less severely locoed, examined in 1907 
 
LOCOWEED DISEASE OF SHEEP 420 
 
 averaged over 7,000,000 red corpuscles, with hemoglobin averaging 85 per 
 cent. The hemoglobin estimations on ten healthy sheep gave an average 
 of 87 per cent; on fourteen locoes the average was 78 per cent. 
 
 Now these figures given by Marsh show that in none of his cases was 
 the hemoglobin reduced to an extreme degree even in the worst cases re- 
 corded, while in the sheep it was relatively insignificant. Although the 
 red corpuscles in some of the severe cases were reduced nearly one-half, it 
 seems peculiar, with the high hemoglobin count, that the anemia alone 
 should be severe enough to explain the remarkable and characteristic 
 serous collections in the heart, spinal canal, and elsewhere. 
 
 With regard to the white blood corpuscles Marsh states, (p. 96), that 
 "An average of twelve locoes in 1907 showed 3,735 white corpuscles." 
 This is the only observation which he records upon the white corpuscles, 
 and it cannot be reconciled with his conclusion (p. 114) that the blood was 
 "commonly rather rich in leukocytes." According to Marek {Klin. Diag- 
 nostik der inneren Krankheiten der Haustiere, pp. 869-887), the white cor- 
 puscles of cattle vary between 7,000 and 10,000 during health, so that 
 Marsh's average of 3,735 actually shows a decided reduction and not an 
 increase. According to Marek the red corpuscles of cattle vary in health 
 between 5,000,000 and 7,000,000 per 1 cc, the hemoglobin averaging 65 
 per cent by the Gowers, or v.Fleischl methods of estimation, which would 
 give a somewhat higher normal reading by the Tallquist method employed 
 by Marsh. In sheep, according to Marek, the normal red count runs from 
 8,000,000 to 11,000,000; hemoglobin about 55 per cent. Comparing these 
 standards of healthy livestock with blood determinations recorded by 
 Marsh, it is seen Marsh records no cases of severe anemia, and it seems im- 
 probable that what he calls "serous accumulations" were the result of 
 anemia. 
 
 Marsh studied loco disease in sheep during 1906 and 1907. During 
 1906, sixty-three yearling bucks and six lambs were studied. All were sup- 
 posed to be locoed at the time they were received, and some were very 
 weak and in bad general condition (p. 66). Soon after the first lot of bucks 
 were received at the experimental camp, they were fed upon hay mixed 
 with locoweed {Aragallus lamherti). Only twelve of these '' locoed" animals 
 would eat the weed at all and even they wo\dd only nibble at it. The others did 
 not eat the ylant at all, although they were locoed sheep in bad general con- 
 dition — 'presumably advanced locoes (italics are mine). As the season wore 
 on all of them ate more or less locoweed, just how much could not be deter- 
 mined. There were some which ate nothing but locoweed. It is to be ob- 
 served that these sheep were "'locoed'' when Marsh received them but 
 
430 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 they did not form the locoweed hahit until some time later. Thirty-three 
 of the sixty-five sheep were examined at autopsy, disclosing 23 cases of 
 sheep fly disease, more or less severe; 23 cases of infection with Thysanosoma 
 actinioides; a serous coagulum in the epidural space of the spinal canal 
 eighteen times; inflammation of the fourth stomach thirteen times; blood 
 clots in the lateral ventricles nine times, etc. Upon these findings, and re- 
 gardless of the fact that his "locoed" animals did not eat locoweed, until 
 forced to it. Marsh concluded (p. 70) that "The principal difficulty with 
 most of the animals in 1906 was the loco poison, with the effects complicated 
 by parasites." He examined more sheep the next year, however, and, 
 though he gives no details of the second group of sheep, he states; "the 
 chief trouble with most of the sheep in 1907 was caused by the parasites, 
 and that the loco had little if anything to do with their condition." He 
 then goes on to make the significant statement : 
 
 The general appearance of the bands of sheep in 1906 and 1907 was the same, and 
 not only the author, but experienced sheepmen, declared that both bands were locoed. 
 In the majority of cases it was only by postmortem examinations that the diagnosis 
 could be confirmed. 
 
 It is perfectly obvious that this statement by Marsh at once knocks the 
 props from under the carefully constructed and elaborate group of symp- 
 toms which he gives as characteristic of loco disease. At least in the case 
 of sheep these symptoms are not of differential value, and it is certainly im- 
 possible to detect the slightest difference between the photographs of 
 Marsh's locoed sheep, and photographs taken by Professor Chesnut of the 
 sheep studied by me. 
 
 Marsh tries to redeem his position by adding, (p. 70) : 
 
 If the habits of the sheep are observed there is a marked difference (between 
 locoed sheep and those suffering from parasitic disease). The sheep affected with 
 Oestrus ovis, except when they are in very bad condition, keep together like normal 
 animals, and show a preference for good food, although they may at times eat loco. 
 The locoed sheep on the other hand, are more erratic, and develop a solitary habit 
 to a greater or less extent. They show, too, a marked fondness for the locoweed. 
 At the same time, when one is dealing with a considerable number of sheep, it is a 
 matter of much diflficulty to separate the locoed animals from those affected with the 
 grub in the head. 
 
 Marsh does not even consider the difficulties of differentiating loco 
 from any other prevailing parasitic diseases of sheep except the sheep fly 
 disease. Moreover, the force of his argument is lost when it is observed 
 that his own typical locoed sheep of 1906 ate the locoweed either not at all or 
 only sparingly (p. 67-68), and when it is added that the sheep studied by 
 
LOCOWEED DISEASE OF SHEEP 431 
 
 me, which ate abundantly of locoweed, were not erratic and developed a 
 solitary habit only as starvation and parasitic disease brought them nearer 
 to death. In other words the clinical symptoms given by Marsh do not 
 differentiate locoed sheep from other ill sheep not locoed. In another place, 
 (p. 92) Marsh himself acknowledges that this is the case, for he says, "after 
 some experience we could, by postmortem examinations, distinguish locoes 
 readily, but it is very difficult before death to tell a locoed sheep from one 
 suffering from grub in the head." 
 
 If we compare Marsh's findings with the findings in the typically locoed 
 sheep studied by me, it becomes perfectly clear, that while the symptoms 
 were often strikingly similar, not one of my typical locoes presented the 
 anatomical changes which Marsh found to be characteristic of loco disease 
 in horses, sheep and cattle. In other words, sheep suffering severely from 
 what is everywhere called "loco disease" in Montana, differ in important 
 essentials from animals suft"ering severely from what is called "loco disease" 
 in Colorado and Nebraska. That is to say. Marsh's work serves to empha- 
 size the trutli of my conclusion that "loco disease" is not a clinical entity, 
 but is a term used by Western raisers of live stock to designate several 
 widely different forms of stock disease. 
 
 The exact and final diagnosis of locoweed appears then to depend chiefly 
 (at least in sheep) , upon finding a peculiar coagulum in the epidural space 
 of the spinal canal, or within the spinal canal. Such a lesion in the central 
 nervous system is unusual, except in diseases such as those referred to 
 below. That this material is a serous effusion, as Marsh describes it, is 
 incompatible with its occasionally being found in a state of organization, 
 as described by Marsh (p. 95, p. 97), and by Peters and Sturdevant. The 
 description suggests that the material was an infl.ammatory exudate. That 
 such an accumulation should occupy, not only the spinal canal, but a posi- 
 tion between the dura and the periosteum, is peculiar. That an effusion of 
 such a nature in such a situation, and one capable of undergoing organiza- 
 tion should result from eating a poisonous plant is little less than amazing. 
 And yet this lesion is, after all, the most important feature of Marsh's 
 description. It is easy enough to find symptoms hke those of his locoes 
 in several other diseases described in veterinary text books; while anatom- 
 ically the catarrhal condition of the stomach and even the ulcers are not 
 distinctive of loco poisoning, and the other lesions are relatively unimpor- 
 tant. This makes a detailed description of the lesions in the central ner- 
 vous system essential to the establishment of Marsh's disease. Such a 
 description including microscopic and parasitologic studies has not been 
 furnished. 
 
432 UNIVERSITi' OV VIRGINIA PUBLICATIONS 
 
 In summing up Marsh's work, it seems that he has called attention 
 to a disease which develops in some of the animals which eat lt)COweed. Not 
 all loco eaters get it, but chiefly those which eat locoweed almost exclusively. 
 There are great individual differences in susceptibility among animals to 
 the poisoning. Pecuhar nervous and mental symptoms with progressive 
 weakness, paresis, or partial paralysis of the hind quarters mark the prog- 
 ress of the disease, together with an increasing tendency to eat locoweed. 
 The disease develops suddenly two or three months after beginning to 
 eat the weed. The animals die of starvation, and at autopsy show serous 
 effusions; a peculiar exudate in the vertebral canal, either outside the dura 
 or around the spinal cord, with congestion of the vessels of the brain and 
 occasionally hemorrhages into the lateral ventricles. There is congestion, 
 or ulceration, or both, in the stomach of horses, and in the fourth stomach 
 of cattle or sheep. The anatomical condition may vary more or less in 
 regard to the central nervous system and the stomach. 
 
 Several diseases have been described which somewhat resemble Marsh's 
 "loco disease." Pica, or licking disease (Nagesucht; Lecksucht), is inter- 
 esting, as it also bears a relation to the soil conditions, and to certain hays 
 in the diet. This disease, which, according to Hutyra and Marek {Spezielle 
 Pathologie und Therapie der Haustiere, 3rd edition, vol. 1, p. 960), affects 
 cattle almost exclusively, when confined to stables for long periods, is 
 produced by certain kinds of hay, depending upon whether the hay was cut 
 before or after the bloom, etc. Hay from certain localities only will produce 
 the disease, and there is apparently an obscure relationship between the 
 disease and the poverty in soda and lime salts, or excess of potash salts 
 in the hay. The symptoms of the disease are like locoism, and the gastric 
 mucosa is infljamed but there is no description of any spinal exudate. 
 
 Catarrh of the fourth stomach, chiefly in cattle, would readily pass for 
 loco disease except that no special changes have been described in the cen- 
 tral nervous system. It is interesting to note that this disease may follow 
 various kinds of improper food, and that highly nitrogenous foods like 
 vetches may produce it. 
 
 Of more interest are the descriptions of meningo-encephalitis, for here 
 the description both of symptoms and of anatomical changes agree rather 
 better with Marsh's account of loco disease. Law {Veterinary Medicine, 
 vol. Ill, 3rd ed. p. 95-6) makes the foUowing statement: 
 
 Among the most common causes of encephalitis in horses is an injudicious dietary. 
 Overfeeding with grain, but especially with grain and seeds that are rich in albumi- 
 noids, deserves the first mention. The various leguminous seeds, peas, beans, tares, 
 vetches, and the ripened leguminous fodders, clover, alfalfa and sainfoin, are espe- 
 
LOCOWEED DISEASE OF SHEEP 433 
 
 cially to be incriminated. These are usually most dangerous when in the stage of 
 advanced ripening and yet not fully matured, evidently indicating the development 
 of narcotic poison at this stage. Such poisons are found habitually in certain species, 
 like the chick vetch (Vicia cicera), which produces paralysis if fed to the extent of 
 
 more than one-twelfth part of the ration With sound judgment and in 
 
 well balanced rations, all such agents can be fed to advantage ; it is only when fed 
 exclusively or to excess as the heavy ration that thej' are to be feared. 
 
 The symptoms of this disease are largely those of Marsh's loco disease, 
 though the disease runs a fatal course more rapidly than appears to be 
 usual in Marsh's cases. There is a fairly close resemblance between the 
 anatomical findings so far as can be judged by reading the accounts of the 
 two diseases. 
 
 Law does not make the distinction very clear to the reader between 
 meningo-encephalitis and the epizootic cerebro-spinal meningitis of horses. 
 The latter disease is known in Idaho (Law), and both symptoms and ana- 
 tomic changes are largely those of the loco disease of Marsh. 
 
 Hutyra and Marek (vol. 2, p. 624, &c.; and p. 634-645), differ somewhat 
 from Law in their description of the two last described diseases, the chief 
 difference being that they lay little stress upon the food, and attribute each 
 disease to a specific bacterium. In their discussion of the differential diag- 
 nosis (p. 632) they outline several diseases which would undoubtedly pass 
 for loco on the ranches. Until Marsh pubhshes his microscopic and bacter- 
 iological studies it will be impossible to decide whether Marsh's loco disease 
 is identical with meningo-encephalitis or with enzootic cerebro-spinal 
 meningitis, but in the meantime it seems rather more probable that Marsh's 
 disease is allied to meningo-encephalitis. 
 
 F. THE LOCO PROBLEM. 
 
 Crawford's review of the literature sets forth strikingly the state of 
 interminable confusion in which the loco problem has been involved since 
 the very beginning, a state due to the vagueness of the definition of loco 
 disease, and to the discrepancies in the description of symptoms, in the 
 statements of fact, and in the results of experiment. Crawford himseK 
 decided that a poison can be extracted from some loco weeds but not from 
 others. This fact may yet be established in spite of Alsberg's contention 
 that the poison is not barium, a contention supported by Marsh. My 
 studies failed to reveal any indications that the animals were poisoned by 
 locoweed, while Marsh is fully satisfied that he has established the poison- 
 ous activity of locoweed beyond all doubt. Even Marsh found that eating 
 locoweed does not always produce loco disease, and he lays emphasis upon 
 
434 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 the persistent, and almost exclusive use of the plant as more or less neces- 
 sary in order to produce poisoning. There seem to be exceptions even to 
 this rule, due to great individual differences among animals in their tolera- 
 tion for the plant. Many animals actually gain weight on a loco diet. 
 
 At the present the work of Crawford, Marsh and myself seems to justify 
 opinions upon several aspects of the loco problem, provided we temporarily 
 concede that Marsh's disease results from the use of the locoweed and is 
 not due to bacteria or parasites. 
 
 1. Some locoweeds, including Aragallus lamherti and Astragalus mollis- 
 simus, may exert a deleterious action upon live stock. Apparently not all 
 locoweeds are equally injurious. That the deleterious action is due to 
 a definite poison in the weed, as claimed by Marsh does not seem to be 
 established. 
 
 2. There are wide individual variations in the results obtained from 
 feeding live stock upon locoweed. Some animals die; others may actually 
 gain in weight for a certain length of time. Animals may eat the weed as 
 part of their ration for years with no bad results. 
 
 3. It requires a large amount of locoweed to produce symptoms. The 
 proportion of locoweed in the diet must be large; in fact in locoism the 
 animals seem to feed chiefly on the weed. Sheep and lambs feeding on the 
 weed as freely as they wanted it were not locoed after eating the weed A. 
 spicatus for over forty days, while the closely allied species A. lamherti ap- 
 parently produced locoism in Marsh's cattle and horses after two to five 
 months of feeding. 
 
 4. It is an easy matter to make the animals eat locoweed. It is only 
 necessary to reduce the amount of available food, or of available fresh 
 green food, for a short time in order to start sheep eating the weed. 
 They will eat it readily — more readily than other grasses, apparently — 
 but not exclusively, as a rule. 
 
 5. The disease described by Marsh as "loco disease" bears a certain 
 resemblance to meningo-encephalitis. 
 
 6. There are several other diseases of live stock on the Western ranches 
 which are generally regarded as loco disease. 
 
 7. Underfeeding or improper feeding appears to be a very important 
 factor in causing losses among the live stock. Entire flocks of sheep may be 
 underfed if the range is overstocked; or if several flocks in quick succession 
 pass over the same range; or if the season is a poor one for the growth of 
 range grass. The younger and weaker members of a band of sheep will 
 always suffer most from underfeeding, as they cannot keep in the front 
 ranks where the best food is, and they should be particularly cared for, or 
 
LOCOWEED DISEASE OF SHEEP 4'\n 
 
 even removed, while they are still in good condition, and fed up in a group 
 by themselves. 
 
 8. Parasitic diseases, passing as "loco disease" are widely spread among 
 the sheep of Montana, and probably throughout the West. The parasites 
 which have come to light during the loco studies are: 1st, the "fringed tape- 
 worm" {Thysanosoma actinioides) : 2nd, a wire worm of the stomach 
 (Ostertagia marshalli) : 3rd, a lung worm; 4th, in sheep which are in poor 
 condition the ubiquitous sheep fly disease may produce serious or fatal 
 illness. The other parasites observed such as the Sarcocystis tenella are of 
 less serious moment. 
 
 9. The hygenic conditions on the ranches, around the bedding grounds 
 for the sheep, and at the watering places, especially in the latter situation 
 seem peculiarly favorable for the wide dissemination of the parasitic dis- 
 eases above mentioned. It does not seem at all probable that the loco 
 studies have brought to light all of the diseases masquerading as "loco 
 disease." 
 
 The unexpected development of the loco work pointing to underfeeding 
 and parasitic infections leads to problems of immediate importance, 
 so great as to overshadow the original loco problem. It would be very 
 interesting to continue to experiment with the loco plant, but the call 
 of the hour is to combat the losses of live stock by tackling the feeding 
 problem, and by making a thorough medical survey under the direction of 
 trained parasitologists to determine the nature and extent of prevailing 
 parasitic diseases, and to inaugurate measures to combat them. Further 
 investigations of the locoweed at the present time will serve only to post- 
 pone the day of relief for the stock raisers. Not until the two problems of 
 underfeeding and infection have been attacked successfully can we hope 
 for a satisfactory settlement of the loco problem. 
 
 Even in the case of Marsh's disease it will be necessary to do much 
 work before Marsh's recommendations can be justified. He advises that 
 the locoweed be exterminated by combined action of the individual rancher, 
 .the state and the nation. The enormous cost of such an undertaking calls 
 for the most careful work to justify it. It will not be until it has been proved 
 that Marsh's disease itself is not dependent upon some microorganism; 
 until it has been clearly established that it does not exist outside of the 
 locoweed belt, and that only animals eating the weed are victims of the 
 disease; and until the food value of the weed, and its value as part of a 
 ration have been learned — not until these matters are settled can Marsh's 
 recommendations be advocated. If Law is correct in the quotation given 
 above, and if the locoweed is like its relatives in the plant kingdom, it may 
 
436 UNIVERSITY OF VIRGINIA PUBLICATIONS 
 
 well be found that the locoweed is a good food if used in moderation and 
 in association with other foods and at certain seasons of the year. Both 
 my animals and Marsh's gained in weight upon a locoweed diet. Disaster 
 followed only the prolonged and almost exclusive use of the weed by his 
 animals. On the other hand, recent work in the Bureau of Animal In- 
 dustry lends support to my view that the parasitic diseases must be 
 attacked if the Western live stock industry is to be properly conserved. 
 Recently Hall (27th Annual Report Bureau Animal Industry, 1912, p. 419), 
 referring to the parasites of Western sheep, says, "Even relatively light 
 infections are apparently sufficient to cause the death of an animal in ad- 
 verse weather conditions or during periods when food is scarce." Moreover, 
 evidence is accumulating to support the opinion expressed by Curtice a 
 generation ago, to the effect that the "fringed tape-worm" does more harm 
 to Western sheep than any other internal parasite, (Ransom: Report 
 Bureau Animal Industry, 1911, p. 60). In view of the prevalence of the 
 parasitic diseases when they were looked for, it seems not unreasonable to 
 expect that an attack upon these diseases combined with an attack upon 
 the feeding problem will clear up the majority of the "loco diseases." It 
 seems even more probable that such a campaign will most surely and speed- 
 ily diminish the huge losses among the Western live stock. 
 
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 19. Locoweed Disease of Sheep. By Harry T. Marshall. Vol. I, No. 19. Price 
 
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