566 DISEASES OF THE HORSE. 
tion in cattle. These are especially by ingestion; that is, by taking up 
the germs with the feed, water, or other means, which have become 
contaminated with the germs. The infection through the genital 
organs is probably not so frequent, but in this regard the stallion no 
doubt plays an important réle in the spreading of the disease. Scho- 
field considers this method of infection as the principal source of 
spreading the disease. 
It must be considered that in infected stables the germs may be 
present throughout the premises, and by keeping animals which have 
aborted in such stables a contamination of feed and utensils may con- 
tinually take place, since the aborted mares usually discharge a con- 
siderable quantity of material which is often heavily charged with the 
germs. The germ is taken up by the body with the feed or water, 
passing from the intestines into the blood, and from there is carried 
to the genital organs, where it finds suitable conditions for its de- 
velopment. Milk from an infected mare may also contain the germ, 
and colts may become infected by sucking the milk of infected 
mothers. In such instances the infection may remain dormant until 
the colt develops and becomes pregnant, when the organism, finding 
a condition suitable for its development, produces the disease. 
On the other hand, stallions used in covering infected mares may 
be carriers of the germs, and when used for the breeding of healthy 
animals may in this manner readily transmit the disease to them. 
Diagnosis.—Contagious abortion may be diagnosed by the changes 
which occur in the fetal membranes, and also in the expelled feces. 
In order, however, to substantiate a diagnosis with certainty, demon- 
stration of the germ by miscroscopical examination is necessary. 
The occurrence of frequent abortions among the mares in a stable is 
also an additional evidence of the contagious character of the mal- 
ady. It must be considered that at times infected mares’may carry 
the fetus to full maturity, in which case the diagnosis is possible only 
by blood examinations in a laboratory. 
Infected animals usually abort only once; however, in a certain 
proportion of cases they may abort even two, three, or four times in 
succession. 
Animals which establish a tolerance for the infection, and carry 
the fetus to full maturity, may nevertheless remain a source of dan 
ger for spreading the disease. : 
The tests used in laboratories for the diagnosis are the agglutina- 
tion and complement-fixation tests, by which the disease may be diag- 
nosed from a sample of blood from a suspected animal. Such tests, 
however, have to be confined to the laboratories, which are equipped 
for such work. 
Treatment and prevention—Medicinal treatment is usually of no 
avail, and all efforts should be directed toward the prevention of the 
