INFECTIOUS SWINE DISEASES IN THE UNITED STATES. 
821 
liog cholera was not present. In these cases the swine-plagne 
bacillns was obtained. 
The disease in these herds invariably ran a rapidly fatal 
course, and in many herds over ninety per cent, of the hogs died. 
The most pronounced symptom observed was a severe cough 
which was brought on if the sick animals were forced to rim. 
This, with the refusal of food, were the only ones reported by 
the owners. The origin of the disease had been traced by sev¬ 
eral local health officers to a drove of swine which had been 
brought into the locality and sold. While these observations 
cannot be considered as conclusive evidence of the singleness of 
the disease, as a careful bacteriological examination was not 
made of all of the animals which died in a single outbreak, the 
occurrence of uncomplicated pneumonia in animals in various 
stages of the disease in the different herds is highly sngo-estive 
that the disease was pure swine plague in epizootic form. 
During the past year I have examined several animals from 
a number of outbreaks of infections swine disease in the State 
of New York. In two of these outbreaks the lesions found in 
the pigs examined were pneumonia with and without pleuritis. 
The spleens were usually enlarged. The intestines were not 
affected. The bacteriological examination revealed the presence 
of swine-plague bacteria, but hog-cholera bacilli were not found. 
In a few outbreaks there were mixed infections such as described 
by Smith, and later by Welch and Clements. 
These investigations support the conclusions of Dr. Smith 
that swine plague is an independent disease although it often 
exists associated with hog cholera. An explanation for the fre¬ 
quency of the latter condition will be suggested in a later para¬ 
graph. 
To summarize, the differentiation of these diseases by their 
morbid anatomy is, in typical cases, not difficult. In hog chol¬ 
era there are ulcers in the intestines with enlarged and often 
haemorrhagic lymphatic gland, engorged and darkened spleen, and 
usually changes in the kidney and liver. In swine plague there 
is more or less hepatization of one or both lungs with or with- 
