HOG CHOLERA AND SWINE PLAGUE. 



219 



juice, and thus the germ-destroying power of this fluid would Ijc 

 diminished. Tissue vitahty in the lungs must be regarded as a 

 very important factor m mcreasing the disease-resisting power of 

 the animal. The laws of hygiene cannot be neglected without 

 rendering animals more susceptible to disease. 



FIG. 79. HOG CHOLERA. < il H R.) 



I^arge intestine, mucous membrane showing general distribution of typi- 

 cal ulcers. I, Ileum; C, caecum or blind pouch. 



How scattered. — The germs of these diseases may be carried 

 from place to place upon shoes, or by wagons, or by driving stock 

 back and forth over an infected area ; or they may be scattered by 

 driving or transporting infected hogs along the public highways. 

 Dogs are comm.on carriers of this disease. Runnino- streams and 

 shallow lakes are also serious factors in the spread of these disease 

 germs. Bowel discharges are very important sources of infection, 

 and if the yards or pens drain into streams or lakes, these become 

 carriers of the infection. Hogs that have died of hog cholera are 

 sometimes thrown into streams or buried in the sand near the 

 edge of a stream or lake, thus infecting the water. 



Practical differences. — Hog cholera germs mav live three 

 months, and possibly longer under favorable conditions. They 

 are hardy and difficult to destroy. Swine plague germs live but 

 a short time, perhaps two or three weeks under favorable con- 



