MORBID ANATOMY 77 



tion runs a very rapid course, the animal dying of septicemia. 

 Usually it is more protracted, lasting from a few days to a 

 week or longer. Animals affected with the more chronic form, 

 where there are lung lesions, eat very little or refuse food 

 altogether. They cough considerably, especially when forced 

 to run. The back is usually arched and the groins sunken. 

 The whites of the eyes are reddened. The skin over the 

 ventral surface of the body, nose and ears is frequently flushed. 

 The cough, however, is the most reliable indication we have 

 of swine plague ; but in some cases of hog cholera the coexist- 

 ence of broncho-pneumonia also causes the animal to cough 

 when forced to move rapidly. 



§ 71. Morbid anatomy. There are many known varia- 

 tions in the appearance of the internal organs of hogs which 

 have died of swine plague. The characteristic lesions are, as 

 previously stated, to be found in the lungs. Frequently the 

 abdominal viscera appear to be normal, although a careful 

 examination will usually reveal slight changes. In the lungs, 

 however, the disease is ordinarily obvious. 



The variety of lesions produced by the inoculation of 

 swine plague bacteria is not so great as that observed in the 

 naturally contracted disease. While there are outbreaks in 

 which considerable uniformity is observed, there are others in 

 which each animal is a surprise to the pathologist. In general 

 it may be stated that the lungs and the digestive tract are the 

 chief seats of the disease, though other organs, notably the 

 lymphatic glands, are .secondarily involved. The disease is 

 localized in the lungs and in the digestive tract probably 

 because the bacteria gain entrance through the respiratory and 

 digestive passages. 



The lungs have been found diseased in nearly every out- 

 break which has been investigated. In some outbreaks the 

 lung lesions predominated and pneumonia was the direct cause 

 of death. In individual cases, pneumonia is absent but 

 pleuritis and interlobular edema are generally present. In a 

 few instances interlobular emphysema of the lungs has been 

 observed. With pneumonia the .seat of the lesion varies : 



