LOCOWEED DISEASE OP 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 suffering severely from what is called "loco disease" 

 in Colorado and Nebraska. That is to say. Marsh's work serves to empha- 

 size the truth 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 inflammatory 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 fimd symptoms like 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 estabhshment of Marsh's disease. Such a 

 description including microscopic and parasitologic studies has not been 

 furnished. 



