564 DISEASES OF THE HORSE. 
animal fails to pick up one of the hind feet as freely as the other, 
or both may become affected at the same time, at which time knuck- 
ling isa common symptom. Labored breathing is occasionally noted. 
When the paralysis of the hind limbs starts to appear the disease 
usually progresses rapidly. The horse goes down, is unable to rise, 
and dies in a short time from nervous exhaustion. The appetite 
usually remains good up to the last. ; 
Although a case of dourine may now and then recover, as a rule 
the disease is present in the latent stage. Bad weather, exposure, 
insufficient feed, and complicating diseases like influenza, distemper, 
or in fact any condition which tends to lower the vitality of the ani- 
mal, may hasten the termination of the disease. 
Diagnosis —The complement-fixation test furnishes by far the 
most reliable means of diagnosis and is especially valuable in a 
chronic affection of this character, when the symptoms manifested 
are variable and frequently so obscure as to escape observation. This 
is a laboratory test requiring special facilities and the services of a 
trained bacteriologist. 
Treatment.—Little benefit can be obtained from medicinal treat- 
ment, nor is such treatment desirable in this country, where the 
disease has existed only in restricted areas, and where sanitary con- 
siderations demand its prompt eradication. 
INFECTIOUS ABORTION IN MARES. 
Infectious abortion (also known as contagious abortion, epizootic 
abortion, enzootic abortion, slinking of colts) is a disease of mares 
which from a specific cause results in the premature expulsion of 
the fetus and its membranes from the uterus. It is characterized by 
an inflammatory condition of the female reproductive organs. 
The contagious nature of the disease had not been recognized 
until recently, the disease being principally attributed to various 
conditions, such as traumatic influences, various infectious diseases, 
spoiled feed, drugs, and other factors. Ostertag was the first to 
study premature births in mares, attributing as the cause of the same 
a streptococcus, which he was supposed to have been able to use 
successfully in artificially producing abortion, either by inoculations 
or feeding. His findings could not be substantiated by other inves- 
tigators. 
The earliest appearance of the disease in this country was in 1886, 
at which time it caused considerable damage to the horse-breeding 
industry in the Mississippi Valley. Smith and Kilbourne investi- 
gated an outbreak in Pennsylvania in 1893, at which time they 
incriminated another germ belonging to the paratyphus B group 
as the causative factor of the disease. These findings have been sub- 
