LESIONS IN THORACIC CAVITY 149 



but these are not characteristic of cholera, as are the hemorrhagic 

 spots just spoken of. 



Microscopic examination of the heart muscle usually shows 

 about the same changes that were found in the spleen, liver, and 

 kidneys. The cells are pale and indistinct, the individual cells 

 are broken up and fragmented, and here and there are seen e vi- 

 olences of beginning fatty degeneration, due to the action of the 

 toxins of the disease upon the tissue. In cases of acute hog-cholera 

 the pronounced weakness of the animal and death are in a large 

 measure due to the severe action of the poison of the germs upon 

 the heart muscle, weakening its power so as to reduce the force of 

 the circulation and also finally producing rapid heart failure and 

 death. 



Changes in Lungs.— Here we find the greatest variation of 

 lesions of any part of the body. So widely different are the changes 

 produced by cholera in the lungs in different cases, in different 

 epidemics, and in widely scattered sections of the country that it 

 has led to many heated discussions among veterinary authorities 

 as to whether or not it is the same disease which produces these 

 widely dissimilar appearing lesions. 



Up to a few years ago the classification was generally made into 

 two diseases — hog-cholera and swine plague. The name hog-cholera 

 was applied to that disease which made itself manifest by pro- 

 nounced changes in the abdominal cavity, with inflammation and 

 ulceration of the bowels, while the name swine plague was apphed 

 to that disease which showed marked lesions in the thoracic cavity, 

 especially in the lungs, and few if any lesions in the bowels. 



A few years ago one of the leading veterinary pathologists of 

 this country investigated a number of cases of supposed cholera, 

 which showed very pronounced symptoms and lesions in the 

 thoracic cavity and few if any changes in the bowels. He believed 

 this condition to be other than cholera, and designated it an infec- 

 tious pneumonia. His theory has since been practically abandoned, 

 as it has been shown by repeated experiments that blood taken from 

 animals suffering with this so-called infectious pneumonia, and 

 injected into young shoats, will produce a form of the disease show- 

 ing typical lesions in the bowels, kidneys, and spleen as well as in 

 the lungs. 



