386 Veterinary Obstetrics 



tervals, after fertilization has occurred, and will continue to 

 copulate regularly for two, three or more estrual periods, in spite 

 of the existence of pregnancy. In a case which we personally 

 observed, the cow was bred for three successive estrual periods, 

 to a bull of one breed the first time, and to one of another breed 

 during the last two periods, and finally gave birth to a calf at the 

 proper time from the first breeding, which showed the character- 

 istics of the breed of the first bull. Similar observations are 

 made in all our domestic animals, though not so frequently as 

 in the cow. 



It is quite generally believed that copulation in an advanced 

 state of pregnancy is liable to induce abortion and numerous 

 cases have been cited to apparently demonstrate the fact. In 

 one case which we observed, the cow showed signs of estrum at 

 about the close of the eighth month of pregnancy and was bred. 

 On the following day abortion took place. The conclusion was 

 that the copulation had caused the abortion. This rnay or may 

 not have been true. The abortion may have been due to the 

 same causes as the estrum, or we might say that possibly the 

 abortion, or rather the death of the fetus preparatory to its ex- 

 pulsion, had induced the signs of estrum and led to copulation 

 with the male. 



While the cessation of estrum is an important indication of 

 pregnancy, it is evidently not final nor wholly reliable ; a non- 

 pregnant animal may cease to show signs of estrum, as we have 

 already related when discussing sterility, while a pregnant one 

 may show signs of estrum at any time during gestation and 

 copulate freely with the male. 



In our domestic animals there is usually noted, as a conse- 

 quence of impregnation, a more tranquil disposition of the 

 female, as a result of which she tends to take on fat during the 

 earlier stages of gestation and, as we have already remarked, 

 this tendency is made use of in preparing animals for slaughter. 



Toward the close of pregnancy, animals apparently become 

 lazy and are not capable of performing certain kinds of move- 

 ments which require agility, such as running and jumping, with 

 the same ease as those which are not pregnant. But these 

 changes are not well marked and the mare which is kept regu- 

 larly at work suffers but little inconvenience so long as the labor 



