376 The Diseases of Animals 
CONTAGIOUS ABORTION 
Contagious abortion is most common in _ cows, 
although it sometimes occurs among mares, when large 
numbers are kept together, as on some of the ranges 
of the West. In some dairy regions, contagious abor- 
tion is one of the most serious diseases that dairymen 
have to contend with. After the disease is once estab- 
lished in a locality, it is difficult to eradicate it entirely. 
The cause of contagious abortion is believed to be 
a germ, or perhaps several kinds of germs. The dis- 
ease is transmitted from an animal that has aborted 
to a pregnant animal, by means of discharges from the 
vagina or by the foetal ealf or the membranes. It 
seems probable that the disease can be communicated 
by a bull that has served a cow that has aborted. 
Cows may abort at any stage of pregnancy, but the 
disease occurs most frequently after the fourth month ; 
earlier than this there are few symptoms. Sometimes 
there is discharge of mucus from the vagina, and the 
vulva may be slightly swollen. There may be small 
yellow ulcers on the mucous membrane lining the vagina, 
which ean he seen hy opening the vulva. <As the cow 
is farther along in pregnancy, the signs of abortion 
are those of approaching parturition; there may be a 
rope of mueus hanging from the vulva, the milk 
secretion may start, and the eow be “down in her 
hips.” 
When a cow shows signs of aborting, or has aborted, 
she should he isolated from other cows, and the place 
where she has stood should be thoroughly disinfected 
