CHAPTER V 



SYMPTOMS AND LESIONS 



FOLLOWING the subcutaneous injection of a 

 small quantity of hog cholera virus, or the feeding 

 of material containing it, symptoms of the disease 

 usually appear between the fifth and eighth days. 

 In herds through which the disease is spreading, 

 several weeks are often required for it to reach 

 all individuals, but this delay must be regarded 

 as due to failure of some of the hogs to take up the 

 virus, rather than as a prolonged incubation 

 period. The incubation period usually given va- 

 ries between four and twenty-one days, but in the 

 vast majority of cases symptoms will appear in 

 less than nine days following definite exposure 

 (feeding or inoculation) of susceptible pigs. 



Three forms of hog cholera are recognized, per- 

 acute, acute and chronic. The peracute form is 

 relatively infrequent, but it occurs occasionally 

 among the first few hogs that succumb in an out- 

 break. No definite symptoms have been asso- 

 ciated with this form of the disease, for the af- 

 fected animals are found dead with no history of 

 previous sickness. 



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