Normal Parturition 525 



the fetus through the cutting off of the nutritive supply, includ- 

 ing oxygen. Hence, foals generally perish if dystokia occurs. 

 This is in sharp contrast to ruminants, where the fetus may con- 

 tinue to live for hours after labor has set in. Consequently, in 

 the mare the actual duration of vigorous labor usually does not 

 extend beyond a few minutes and occasionally occurs so quickly 

 in a work mare that she can scarcely be unhitched from the plow 

 and have her harness removed before the living foal has been ex- 

 pelled. In cows which have given birth to a number of calves, 

 the birth act is sometimes almost as prompt, although usually it 

 is more prolonged because the os uteri does not dilate so readily 

 and the labor pains are not so tumultuous and powerful. 



In multiparous animals, the birth of each young animal usually 

 follows quickly upon that of the preceding. A sow may bring 

 forth 8 to 10 young in less than an hour. Sometimes parturition 

 becomes tedious and a sow may be a day or more in expelling the 

 fetuses. 



When the fetus is expelled, the effect upon the umbilic cord 

 will depend somewhat upon the position of the mother, but very 

 largely upon the length of the cord. In the mare, J:he Umbilic 

 cord is quite long and the fetus may be completely expelled and 

 the cord continue intact so long as the animal remains in a recum- 

 bent position. When she arises, the cord will probably rupture 

 and, if not at that moment, it must give way when she turns to 

 examine her young, if the chorion remains attached in the uterus. 

 In some cases, however, the afterbirth immediately follows the 

 fetus and remains attached to it by means of the cord until the 

 foal itself ruptures it by its struggles. 



The umbilic cord of the foal ordinarily ruptures at a point 

 about two inches from the umbilic ring, and just beyond a 

 point where there is a distinct line of demarcation between the 

 cord proper and the cordiform extension of the abdominal wall, 

 which is not covered with hairs. (See Fig. 90 B.) The ex- 

 act point of rupture may vary, however, and the cord may 

 become torn in two, 5 or 6 inches or even more from the um- 

 bilic ring, or it may give way very close to the ring. It has 

 been alleged that the rupture may occur in the ring, but the 

 writer has not observed such an accident and its occurrence 

 may be doubted. The rupture of the umbilic cord is followed 

 by some hemorrhage, especially if the placenta still remains 



