INFECTIOUS DISEASES I47 



portions of the carcasses, eaten by the animals. 

 Infection may also occur through the inspired air, 

 and when hogs affected with tuberculosis are 

 introduced into the herd, all the hogs in the pen 

 may contract the disease. 



Such conditions as act unfavorably on the con- 

 stitution of the pig will, if the germs are present, 

 favor the development of the disease. Close pens, 

 filth, unnatural bringing up, early forcing, etc., 

 all favor its development. Improved breeds of 

 swine are said to contract tuberculosis more 

 readily than the common breeds. Infection has 

 been known to occur by way of wounds, especially 

 castration. 



Symptoms. — In pigs that have become diseased 

 by sucking a tubercular mother, marked symp- 

 toms of intestinal and generalized tuberculosis 

 may be manifested. The pig becomes stunted, 

 " pot bellied," and very thin. The skin and coat 

 present a very unthrifty appearance, and the skin 

 is usually dirty looking and covered with crusts. 

 Digestive disorders, such as diarrhoea, bloating, 

 and vomiting, occur. At times th'e pig is feverish, 

 refuses to eat, and finally becomes very weak. 

 Pressure on the abdomen may cause the animal 

 pain, and, sometimes, hard, knotty masses representing 

 bunches of tubercles are felt. 



In case the lungs are involved, the animal 

 coughs and the breathing may be quick and 

 labored. These symptoms become more marked 

 as the disease progresses. In the latter stages. 



