DIAGNOSIS, DIFFERENTIAL DIAGNOSIS, PROGNOSIS 63 



tern change in swine dead from any cause, es- 

 pecially fat hogs that have died in hot weather. 



Other less characteristic symptoms add evi- 

 dence, but most of them may result from causes 

 other than hog cholera, and it is unsafe to give 

 them too much weight in their relation to diagno- 

 sis. 



Lesions. Lesions constitute our most accurate 

 guide in diagnosing hog cholera, for it is not often 

 that a conclusion can be reached without consider- 

 ing them. Hogs sometimes die of the disease 

 without showing any characteristic macroscopic 

 tissue changes, so if no cause for death is found, 

 additional autopsies should be performed. In 

 case it is necessary to kill a pig for this purpose, 

 it is best to select one that has been sick several 

 days, but not a chronic case. Petechiae and ec- 

 chymoses are the chief changes which character- 

 ize hog cholera, but it is important to remember 

 that in cases of long standing, and in those in 

 which secondary invasion has taken place these 

 primary filterable virus lesions may be so changed 

 in character that they are difficult to identify. 



Assuming that we have before us a carcass, and 

 that hog cholera is suspected, the autopsy will in- 

 clude special examination of the skin, kidneys, 

 bladder, lymph glands, spleen, heart, lungs and 

 laryngeal mucosa, as well as the serous membranes 

 readily accessible, and the digestive tract. The 



