70 HOG CHOLERA 



Having already dealt with the distinguishing fea- 

 tures of hog cholera we will confine our remarks 

 chiefly to characteristics which suggest the pres- 

 ence of these other diseases. 



Swine plague. Swine plague rarely occurs in 

 pure form, it affects only a portion of the animals 

 in a herd, and there are frequent spontaneous re- 

 coveries. There is often a history of recent ship- 

 ping. The incubation period is short (1 to 3 days), 

 acute dyspnea and thumping are prominent symp- 

 toms, and the hogs show more distress than is 

 observed in hog cholera attacks. High tempera- 

 tures are not the rule except during the first few 

 hours of sickness. The characteristic " swine 

 plague pneumonia, " if present in several autop- 

 sies, speaks for the existence of swine plague, but 

 the absence of the filterable hog cholera virus 

 must be clearly established before a diagnosis of 

 pure swine plague is justified. 



None of the pneumonias, with the exception of 

 that associated with swine plague, are accom- 

 panied by the lesions in other organs which char- 

 acterize hog cholera. Usually they occur where 

 pigs are kept in very dusty quarters, or where 

 the floors are cold and damp and no dry litter is 

 provided. Eecent shipping is a predisposing fac- 

 tor, and lung worm and ascarid infestations play 

 an important part in their development. They 

 are sporadic or only slowly transmissible. High 



