40 BULLETIN 106, U. S. DEPARTMENT OF AGRICULTURE. 
Other abortion statistics available to us would not modify essen- 
tially the general picture of the disease. Generally we believe that 
the average rate of abortion in pedigreed herds falls between 10 and 
15 per cent per annum, rising and falling from year to year, unseen 
possibly in the smaller herds for one, two, or three consecutive years, 
then showing itself again, gathering force for a while, and culminating 
in a great explosion of the disease which forces the percentage of loss 
up to 30, 50, or 75 per cent, or even higher. It is not at all rare in a 
group of 10 to 20 heifers pregnant for the first time for the abortion 
loss to reach 90 or even 100 per cent. In small herds of 5 to 15 or 20 
animals, mostly adults, the percentage of abortion is usually far below 
the above ratio. 
SYMPTOMS OF ABORTION. 
The symptoms of cattle abortion are as yet extremely vague. 
They popularly fall into three groups — the signs of impending abor- 
tion, the phenomenon of aborting, and the evidences that abortion 
has occurred. 
The symptoms of impending abortion comprise chiefly tumefaction 
of the udder and of the vulva, vaginal discharge, and sinking of the 
broad ligaments of the pelvis, any or all of which may fail or may be 
deceptive. Tumefaction of the udder is not common unless the preg- 
nancy has passed the fifth month; even then it is not reliable. In 
milking cows it is usually unobservable. The erroneous assumption 
that tumefaction of the udder indicates that a heifer will certainly 
abort leads to the error that the use of certain nostrums have blocked 
an impending abortion. Heifers pregnant for the first time not 
rarely suffer from a severe mammitis or garget as early as the sixth 
month, which has no known relation to abortion. Heifers which 
have never been in calf show at times swelling of the udder, and may 
even milk freely. The sinking of the pelvic ligaments is more indica- 
tive of impending abortion, and may be regarded as an unfavorable 
sign when present, but this is only in a minority of cases. 
The evidences of the act of the expulsion of the fetus are largely 
dependent upon the duration of pregnancy, because the force required 
for its expulsion naturally depends upon its dimensions. In the 
earlier stages of pregnancy no expulsive efforts are seen, and it is only 
by the chance observation of the embryonic sac passing through the 
vulva that the act is observed at all. As pregnancy becomes more 
advanced the expulsive act assumes more and more the general aspect 
of normal parturition. 
If the act of the expulsion of the fetus passes unobserved and the 
afterbirth has come away, there is little to indicate that abortion has 
occurred until the cow again comes in heat. If she is well advanced 
in pregnancy the abortion is very liable to be followed by retained 
placenta, which is usually clearly recognizable. 
