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 locoweed. 



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. 



