566 MANUAL OF POISONOUS PLANTS 



poison cattle because they rarely eat it. Dr. Marsh states that the symptoms 

 described by stockmen were corroborated; these are: 



The lowered head, rough coat, slow, staggering gait, movements showing lack of 

 -muscular coordination, sometimes more or less paralytic symptoms, a generally diseased 

 nervous system, and in the later stages of the disease extreme emaciation. 



The principal pathological changes are pronounced anemia of the whole system, diseased 

 stomach walls, and in acute cases a congested condition of the walls of the stomach; while 

 in chronic cases there are frequently ulcers. Generally speaking, locoed cattle have ulcers 

 in the fourth stomach. There is an excess of fluids in the various cavities of the body. 

 This is especially noticeable in the epidural space of the spinal canal. Here the effusion 

 is more or less organized, presenting the appearance of a gelatinous mass, which is es- 

 pecially abundant in the lumbar region and about the exits of the spinal nerves. In most 

 locoed females the ovaries are found in a diseased condition. 



Dr, Crawford from his laboratory work concludes : 



The symptoms described in stock on the range can be reproduced in rabbits by feed- 

 ing extracts of certain loco plants. Those especially referred to here under the term 

 "loco plants" are Astragalus mollissimus and Astragalus Lamberti ^Oxytropus Lamberti). 



The production of chronic symptoms in rabbits is a crucial test of the pharmacological 

 activity of these plants. 



It is the inorganic constituents, especially barium, which are responsible for this poison- 

 ous action, at least in the plants collected at Hugo, Colo.; but, perhaps, in the future, loco 

 plants from other portions of the country may be found to have other poisonous principles. 



There is a close analogy between the clinical symptoms and pathological findings in 

 barium poisoning and those resulting from feeding extracts of certain of these plants. 

 Small doses of barium salts may be administered to rabbits without apparent effect, but 

 suddenly acute symptoms set in analogous to those reported on the ranges. 



The administration of sulphates, especially epsom salts, to form insoluble barium sulphate 

 would be the chemical antidote which would logically be inferred from the laboratory work, 

 Taut of necessity these sulphates would have to be frequently administered, and their value, 

 after histological changes in the organs have occurred, remains to be settled. But the treat- 

 ment of acute cases of barium poisoning in man is not always successful, even when 

 sulphates combined with symptomatic treatment are employed. The conditions under which 

 sulphates fail to precipitate barium must be considered. 



Loco plants grown on certain soils are inactive pharmacologically and contain no 

 barium. In drying certain loco plants the barium apparently is rendered insoluble, so that 

 it is not extracted by water, but can be extracted by digestion with the digestive ferments. 

 To be poisonous the barium must be in such a form that it it can be absorbed by the 

 gastro-intestinal tract. 



There are plants with barium salts which are not injurious. 



Dr. Marsh found that it is easy to kill the woolly loco weed {A. mollissi- 

 mus) in fenced pastures because it occurs in small patches. The stemless loco 

 weed is of wider distribution and, when in fenced pastures, can be killed but 

 not so easily when it occurs on the ranges. He recommends treatment as fol- 

 lows : 



In regard to the second phase of remedial work, it was found that locoed cattle can 

 in most cases be cured by a course of treatment with strychnin, while locoed horses can 

 generally be cured by a course of treatment with Fowler's solution. The animals under 

 treatment must not be allowed to eat the loco weed and should be given not only nutritious 

 food but, so far as possible, food with laxative properties. To this end, magnesium sulphate 

 was administered to correct the constipation which is almost universal among locoed animals. 

 It should be noted, too, that magnesium sulphate may serve to some extent as an antidote 

 to the poison. 



Dr. C. Dwight Marsh ^ in a recent publication in speaking of this plant as 

 well as the White Loco Weed and the experimental work of the Department of 

 Agriculture, states that they are the weeds which produce the disease from 

 Montana to northern New Mexico, Arizona and in western Texas, but there 

 are many locoed animals where these two species do not grow. In California, 



*The Ivoco-Weed disease. Farmers' Bull., U. S. Dept. Agr., 380. 1909. 



