Spontaneous Abortion in Other Species

Jill Stanek’s blog featured some Aggie News, relating equine behavioral and biological phenomena to the abortion issue.   Pharmer, being Pharmer, can’t pass up such hot issues as animal husbandry  (that’s breeding livestock …ok.)

It’s been noticed that bringing in outside male zebras to prevent inbreeding at zoos has resulted in an extremely high miscarriage (abortion) rate among the mares.    Horses share this difficulty, as do other animals such as some rodents.  In the presence of the males from the home location, the mares which have been bred by outsiders will often lose their offspring.  Some of the mares will copulate with the home males, and if unable to do so will be more  likely to abort.  It is surmised  that this is a biological adaptation to the fact that the male equines will very often kill the offspring which resulted from relations with outside males. It is believed to result in a conservation of energy and resources for the mare to lose the offspring before birth  rather than go through the effort of delivering a foal which will be killed anyway.

In one of the fluffy news pieces describing the phenomenon among horses, it was suggested that the mares could actually will the loss of the pregnancy if the circumstances regarding the presence of non parental males were untoward.  Pharmer supposes that this notion is no more crazy than man-made global warming.

In a somewhat related phenomenon, the  smell of urine from newly introduced  males who did not breed with the female mouse will elicit failure of implantation, but does not cause loss after that stage. This is referred to as the Bruce effect, in which production of a functional corpus luteum is prevented.  This effect is abated by the presence of familiar males, even if they did not breed with the female mouse. The Bruce effect  is not seen in rats, and is a good deal different than what is being observed in horses.




2 thoughts on “Spontaneous Abortion in Other Species

  1. Do horses understand about pregnancy? They may have an instinct to love and care for the foal or colt when it shows up. But that doesn't mean they understand about pregnancy, where the offspring comes from, and what role the male horse plays. That the female horse could not only understand that she is pregnant, but know what that means, where it came from, and will it away if the correct males aren't around is ludicrous. How could the horse will the pregnancy away? Somebody is reading a lot into the horse's biology and into its mind. They probably want to do this to make a justification for deliberate abortions in humans. After all, animals do it. This is nonsense.

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