262 HOG CHOLERA 



i8. Pigs are not usually af- i8. Pigs are not usually affected 



fected by subcutaneous injection by the subcutaneous injection of 



of small quantities of culture. If small quantities of culture. The 



the pigs are killed within i to 3 bacilli are not found except in the 



weeks the bacilli are found in the local lesion. In a few cases fatal 



local lesion and certain of the lym- results are reported, 

 phatic glands. Fatal results are 

 reported in a few cases from these 

 injections. 



19. Feeding cultures to pigs I9- Feeding cultures to pigs 

 which have fasted for 24 hours pro- usually produces no effect, 

 duces extensive intestinal lesions 



with fatal results. 



20. Intravenous inoculation in- 20. Intravenous inoculation in- 

 to pigs causes either an acute sep- to pigs usually produces a septic 

 ticemia or a chronic form of the form of the disease w hich kills in 

 disease in which are produced from i to 2 days. Inoculation into 

 quite typical round, firm, elevated the lungs causes pleuritis, usually 

 ulcers. accompanied by pneumonia. 



Dawson pointed out the serum reaction as a possible 

 means of diagnosis. This test, however, seems of little value 

 until the disea.se has run a course of many days. 



§ 186. Prevention. As hog cholera is caused by a 

 specific organism, the first fact to be determined is to find the 

 channel or means by which it can be carried from an infected 

 to a non-infected herd. The thorough investigations which 

 have been made in the United States Bureau of Animal Indus- 

 try have shed much light upon this subject. The observations 

 of more recent years have confirmed the conclusion reached in 

 the earlier reports of the Bureau concerning the means of 

 spreading this disease. With these results, the pointing out 

 of the ways by which the virus may be disseminated and the 

 methods necessary for checking its spread is no longer ques- 

 tionable and there is a certainty that it can be kept away from 

 individual herds even in the midst of widespread epizootics. 

 A few of the common means of its dissemination are worthy of 

 note. 



I. The virus of hog cholera is frequently introduced into 

 a non-infected locality by the purchase of animals, usually for 



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