DIAGNOSIS, DIFFEBENTIAL DIAGNOSIS, PKOGNOSIS 67 



evidence of acute hog cholera. The "button 

 ulcer" is usually associated with the chronic form, 

 but agents other than the filterable virus may be 

 instrumental in producing it. 



All these hog cholera lesions will not often be 

 found in one animal, but if two or more organs 

 are involved this fact, supported by a history 

 that does not positively deny the presence of 

 the disease, may be accepted as ground for a 

 diagnosis. If more organs are involved the evi- 

 dence is more conclusive. 



AnimaJ inoculation. This method is rarely 

 applicable in actual practice, because it is expen- 

 sive and requires too much time. In very excep- 

 tional outbreaks which present atypical features, 

 and in cases, involving litigation it may be useful. 

 The essentials -of a conclusive experiment may be 

 sunrniarized" thus :. 



1. Blood should be drawn from a hog which has 

 been sick for only a short time, and which carries 

 a temperature near 106 F. 



2. The . blood -should be diluted with sterile 

 water and passed through a filter which retains 

 all microscopic organisms. 



3. Enough of the filtrate to represent at least 

 1 mil of the undiluted blood should be injected 

 into a susceptible pig, preferably one weighing 

 between forty and one hundred pounds. 



4. Twelve days previous and subsequent to the 



