r, are by no
means constant, especially if the abortion takes place in the early
months of pregnancy. The genital organs are usually swollen, showing a
mucous discharge. Immediately before abortion the symptoms are more
aggravated. Following abortion the discharge is more characteristic,
being of a dark-brown color, sometimes even bloody, and contains streaky
or flaky pus. The fetal membranes in all cases are not expelled with the
aborted fetus, but there is a tendency toward retention of these
membranes, which frequently has serious consequences upon the health of
the animal. At times it becomes necessary to resort to manual removal of
the afterbirth, and the inflammation of the uterus and a chronic
discharge usually follow such conditions. The expelled fetuses, as a
rule, die soon after the abortion, and if the expulsion has taken place
at a time close to its full term the fetuses are usually poorly
developed and subject to various kinds of digestive and septic
disorders. The fetuses do not disclose any particular abnormal
appearance on external examination; in many cases, however, the
post-mortem examination reveals inflammatory changes of various organs.

The method of infection has not yet been satisfactorily established;
nevertheless it is essential that we consider as the principal mode of
infection the ways which have been proved for the contagious abortion
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 role in the spreading of the disease. Schofield 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 continually take
place, since the aborted mares usually discharge a considerable 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 development. Milk from an infected
mare may also contain the germ, and colts may become infected by sucking