INFECTIOUS DISEASES. 565 
sequently substantiated by many investigators abroad, as well as in 
this country, notably so by De Jong, Dassonville, and Riviére, and by 
Good and Meyer. More recently very valuable information was 
contributed to our knowledge on this disease by Schofield, of Canada, 
especially with regard to the biological tests for diagnosis. Good 
suggested “Bacillus abortivus equinus” as the name for the specific 
organism. 
The causative agent of this disease is not identical with the germ 
causing abortion in cattle. It exerts its action, however, in a similar 
manner, and appears to have, under certain conditions, a predilec- 
tion for the genital organs of the mare, where it induces certain 
morbid changes whereby a premature expulsion ‘of the fetus is the 
result. The germ is usually present in the fetal membranes and also 
in the aborted fetus. Mares may harbor the infection without dis- 
closing any apparent ill effects. It appears to exert its influence 
mainly upon the female genital organs, where it may induce an in- 
flammatory condition of the uterus. 
The infected animals may carry the fetus through the normal 
period of pregnancy, giving birth to either a normal or a weak colt, 
or again abortion may take place at any time during pregnancy, 
mostly, however, from the sixth to the ninth month. 
Symptoms.—The symptoms suggestive of abortion are frequently 
entirely absent. At times the abortion may be ushered in by symp- 
toms of colicky pains, restlessness, and periodical straining; these, 
however, 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, some- 
_ times even bloody, and contains streaky or flaky pus. The fetal mem- 
branes 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 examin- 
ation; 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 abor- 
