174 HOG CHOLERA 



foci in the liver and a very much enlarged and dark-colored spleen. 

 Guinea-pigs are affected similarly to rabbits, but death does not usually 

 occur until from 7 to 12 days. Pure cultures of the bacillus can be 

 obtained from the blood, liver or spleen of the inoculated animals. 



While the above description applies to the form most frequently 

 encountered, varieties are not uncommon. In 1894 Smith called atten- 

 tion to several varieties of this species. It is interesting to add, that 

 Reed and Carroll have found the bacillus isolated by Sanarelli, and 

 thought by him to be the cause of yellow fever, to belong to this group of 

 bacteria. 



§ 136. Symptoms. The sjaiiptoms of hog cholera are 

 by no means constant. The best informed writers on the sub- 

 ject agree that hog cholera can not, with certain exceptions, be 

 positively diagnosed from the symptoms. Animals suffering 

 from various intestinal troubles frequently exhibit symptoms 

 which ver}' closeh' resemble those of this disease. 



There are two recognizable forms, namely, the acute and 

 the chronic or mild form. In the acute disease, the animals 

 die very suddenly after a few hours or at most a few days' 

 sickness. In the other form, the disease runs a longer course. 

 There is usually a rise of temperature of from i to 3° F. 



The sick animals act dumpish, spiritless and lie quietly 

 in a corner or huddle together usually concealing the head in 

 the litter. They refuse to move when disturbed and are more 

 or less oblivious to their suffering. The appetite varies. In 

 acute cases the animals may eat quite heartily up to within a 

 few hours before death. In more chronic forms they eat fairly 

 well until the end. There may or may not be diarrhoea. Fre- 

 quently the bowels are costive. It is quite common in these 

 cases to have an active diarrhoea during the last few da3'S. The 

 color of the discharge depends largely on the food. \'omiting 

 rarely occurs. The changes in the respiration and the pulse 

 are difficult to determine. There is rarely any cough. Usually 

 there is considerable reddening of the skin on the nose, ears, 

 abdomen and on the inside of the thighs and pubic region. 

 Occasionally this reddening is very marked. The redness is 

 diffuse and more intense as death approaches. In some cases 

 there is a discharge from the eyes. In the chronic form the 

 animal becomes emaciated. These symptoms vary to such an 

 extent that it is sometimes necessary to make a post-mortem 



