INFECTIOns DISEASES 321 



croupous pneximonia, though evidence of septic intoxication is more 

 pronounced than in the latter. The very offensive odor of the expired 

 air characterizes pulmonary necrobacillosis. 



Treatment. — Treatment other than providing good, nourishing food 

 and sanitary surroundings is of little or no avail. 



NECROTIC HEPATITIS 



Hepatic necrobacillosis is not of common occurrence, but some cases 

 have been observed. It is usually secondary to necrotic enteritis, the 

 infection passing through the portal system and metastasizing in the 

 liver. , ^^1 .. -J 



Lesions. — The lesions consist of sharply circumscribed grayish- 

 white areas varying in size from that of a pinhead to a silver dollar. 

 These areas may be surrounded bj^ a fibrous capsule. The density or 

 consistency of the lesion depends upon its age. It may be of the 

 same consistency as the, surrounding liver, it may be dry and mealy, 

 or, if the animal recovers, it may become calcareous. These areas may 

 not cause any irregularity in the size or shape of the liver or the 

 lesion may assume the nodular form, the nodules projecting from the 

 surface of the liver. The surface nodules have a raised border and a 

 depressed center, and are quite characteristic in appearance. 



Symptoms. — No definite symptoms have been attributed to hepatic 

 necrobacillosis other than general digestive derangement. These cases 

 are diagnosed at autopsy. 



Treatment. — The location of the lesions and the nature of the 

 process practically eliminate the possibility of successful treatment. 



NECROTIC SPLENITIS 



Splenic necrosis is a rather common condition in swine. It may be 

 caused by other agencies than the Bacillus necrophorus, but from in- 

 vestigationk thus far conducted it appears that the most frequent 

 cause of necrosis of the spleen is the Bacillus necrophorus. This con- 

 dition is commonly associated with the use of a contaminated hog- 

 cholera virus. The infection is carried in the blood to the spleen. 



Lesions. — The necrotic centers in the spleen are usually encap- 

 sulated, the density of the capsule varying with the length of duration 

 of the process. As a rule, the centers are in the form of nodules. They 

 are of a grayish-white color and usually have a depressed center and a 

 raised border. In size these foci vary from masses half an inch in 



