234 TRANSACTIONS OF THE 



HOG CHOLERA. 



By Robert J. Dawson, V.S., 225 Geary Street, San Francisco. 



Edwin F. Smith, Secretary State Board of Agriculture : 



Dear Sir : Considering that "hog cholera" exists to such an extent, I 

 think it the duty of every veterinarian to investigate in that direction and 

 forward result of same to headquarters. 



I now send you for publication, or whatever purpose you wish, papers 

 written by me stating facts, my opinions, etc. 



I may say that I am continuing my studies in that direction, and hope 

 to forward other details at some future time. 



HOG CHOLERA. 



This name for the disease is misleading, as in the majority of cases 

 there is much constipation of the bowels. Diagnostic symptoms prior to 

 death are not well marked. The animal may linger for several days, and 

 in addition to ordinary symptoms of ill health, red and blue patches upon 

 the abdomen may be seen; these are noticed during the latter stages of the 

 disease. On being called to a number of animals, dying in a mysterious 

 manner, the veterinarian proceeds to make minute inquiries and post-mor- 

 tem examinations, and if necessary microscopic investigations. 



Post-mortem Appearances. — Mucous membrane of intestines shows patches 

 of inflammation, differing from ordinary inflammation, in not being evenly 

 diffused over the surface. Mesenteric glands are altered in character, being 

 inflamed. The lungs, in some cases, are also affected. In fact, in advanced 

 stages of the disease, where the disease has actually produced death, 

 almost all the organs and tissues show signs of the presence of some agent 

 which has produced extensive blood poisoning. Tumefaction or harden- 

 ing of the small glands of the intestines. Ulcers also are frequently 

 . noticed, and these much resemble in appearance those occurring in human 

 typhoid. Inflammation occurs in the lymphatic structures generally, espe- 

 cially those of the intestines. 



Microscopic Matters and Investigations. — In making investigations it is 

 advisable to either kill the diseased animal, or if allowed to. die from 

 the effects of hog cholera, at once make the necessary specimens; as organ- 

 isms, the result of post-mortem decomposition, may develop, and thereby 

 hinder the examination. Baccillus suis is the term given to the hog cholera 

 germ, and they may be found in the excrements, and in all morbidly 

 affected tissues. After the animal has actually become affected, by con- 

 tact with the disease germ, these germs increase in number and alter in 

 character — this is called the period of incubation. With proper heat and 

 an adequate supply of oxygen, they soon develop and grow lengthwise, by 

 a kind of budding process. They cease- to exist when decomposition and 

 putrefaction set in. They are found in very large numbers in the blood of 

 living diseased pigs. Period of incubation varies from three to seven days, 

 after inoculation. It has been proved that virus, after having been exposed 

 to the atmosphere for several days, will yet be capable of producing the 



