124 LABORATORY BACTERIOLOGY 
VII 
DIAGNOSIS OF HOG CHOLERA 
Hog cholera is the epizootic disease of swine caused by a 
filterable virus. The virus is not pathogenic for the small ex- 
perimental animals, and as yet it cannot be cultivated. This 
restricts the means of diagnosis to the nature of the lesions 
and the inoculation of swine with the blood of the hog under 
suspicion. As this inoculation is expensive, and as it usually 
requires from 8 to 12 days for results, the diagnosis is to be 
made from the nature of the lesions by the practitioner in the 
field. Itis often necessary to examine several hogs before one 
showing characteristic lesions will be found. 
Lesions. The lesions by which hog cholera is diagnosed are 
petechial hemorrhages, especially in the kidneys, lungs, or in 
the heart muscle. Sometimes they are very numerous and pro- 
nounced ; in other cases they are few and very small. Button 
ulcers in the intestine are sometimes present. Congestion and 
perhaps hemorrhage in the bone marrow are significant lesions. 
Congested and hemorrhagic lymph glands are suggestive. 
There is often reddening of the skin over the ventral surface 
of the body and about the head. The petechial hemorrhages 
are, however, the most characteristic lesions. 
Inoculation. The diagnosis by inoculation consists in filter- 
ing the blood of the suspected hog through a Berkefeld filter, 
and inoculating a healthy pig subcutaneously with about 2 cc. 
of the filtrate. It will develop symptoms of hog cholera in 
from 5 to 8 days and will die in from 8 to 15 days if the blood 
came from a pig suffering with hog cholera. 
Where hog cholera is suspected it is necessary to send the 
entire viscera. It is often desirable to send the pig itself. 
It is absolutely necessary that the tissues arrive in a fresh 
condition. 
