318 



SWINE PRACTICE 



tive tube of swine and, less frequently, the digestive tube of other 

 animals; therefore the microorganism is found in the feces of prac- 

 tically all animals. Soil, yards, pens, floors — in fact, practically all 

 of the surroundings — easily become contaminated with fecal matter, 

 and the disease may be obtained from anything that has been con- 

 taminated with feces. Infection is usually indirect, although the 

 Bacillus necrophorus may be transmitted from an affected to a 

 healthy animal by contact. 



Channel of entrance. — This infective agent may be successfully 

 introduced into the susceptible swine in food or drink by way of the 

 mouth, upon inhaled dust particles by way of the respiratory organs, 

 or it may be introduced through abrasions of the skin, and, more 

 rarely, into the genital organs during copulation. 



Pig. 93. M>:cR()i!.\ctLi.i)Si.s. 



Lesions. — The Bacillus necrophorus is capable of invading prac- 

 tically any tissue of the body, and the lesions produced so closely 

 resemble each other than one general description will suffice. The 

 lesion consists of a coag'ulation necrosis, the necrotic material later 

 becoming caseated. The local lesion has a tendency to become larger, 

 due to the infiltration of the surrounding tissue with the products 

 of the Bacillus necrophorus. The infection, and therefore the lesions, 

 may occur elsewhere in the body, due to metastasis. There may be 

 general emaciation due to absorption of the products of the Bacillus 

 necrophorus, and tissue destruction. 



The local specific lesion is a sharply circumscribed yellowish or 

 brownish area containing a homogeneous, dry, mealy, or cheese-like 

 substance from which a pungent and disagreeable odor emanates. 



