200 The Diseases of Animals 
through narrow doorways, kicks, blows or sudden 
jumps from the use of the whip. During the later 
stages of pregnancy, strong medicines, especially vio- 
lent purgatives, should not be given. 
The period of gestation, or pregnancy,—that is, the 
time which elapses between the fertilization of the egg 
and the birth of the young,—varies in different animals 
as follows: 
Mare... . about 344 days, or eleven months; mule colt, twelve months 
Cow ....about 280 days, or nine months 
Ewe ... about 152 days, or five months 
Sow ....about 112 days, or three and a half months 
Pitch. ...about 63 days, or two months 
Pregnant animals frequently give birth to their young 
sooner than the period indicated. If the young animal 
is sufficiently developed to live, it is usually called a 
premature birth ; if the fetus is not sufficiently devel- 
oped to live, it is called an abortion. Pregnant animals 
may also carry their young longer than the period 
indicated. 
SIGNS OF PARTURITION, OR APPROACHING BIRTH 
At the close of the period of gestation, signs of 
approaching parturition usually appear. The mammary 
glands become distended, the vulva enlarges, and the 
mucous membranes lining the vagina become congested 
and red. In cows, the hip bones tip forward a little, 
and a small depression on each side of the root of the 
tail appears more marked. The cow is commonly said 
to be “down in her hips.” In mares, a waxy secretion 
