Ask the Vet: Reproduction

Courtesy of AAEP By, Madison Seamans, DVM, MS, Kuna, Idaho

Question: Can I breed any jumping mare by any jumping stallion and expect that the foal will be able to jump the same? What does the latest knowledge about genetics say?

Answer: Although our understanding of equine genetics has been greatly expanded in recent years, we are a long way from recognizing the genes for a given athletic talent. The Equine Genome Project, an international team of scientists, has sequenced, or mapped, all the DNA of the horse. Surprisingly, we only recognize about 2% of the genetic material as “genes” for specific traits. That means we have a map, but we don’t know where 98% of it goes.

In addition, there are “inherited tendencies” that may not be genetic. For example, we know that the mare can transmit undesirable traits like OCD and metabolic syndrome, so females with these traits should not be bred or even carry embryo transfer foals. Maybe there is a “jumping gene”, but we haven’t found it yet. We should be selecting horses that are outstanding in a given discipline, and breeding them. It would not be wise to “settle for” less than the absolute best we can afford.

Question: What are all the different ways of detecting a twin pregnancy in a mare?

Answer: Although there are some hormone tests available to determine pregnancy in mares, the only reliable method of detecting twins is with ultrasound. This is a safe and very effective way of imaging the reproductive tract of a mare and is readily available through most AAEP-member veterinarians.

Question: I have a mare due to foal in about a month. She is a pasture horse and not use to being stalled. I have been told that stalling her when she is close to foaling may stress her too much and I should let her foal in her usual environment. Thoughts?

Answer: Exactly where to put a foaling mare has been a question tormenting horsemen since the first stall was constructed. A stall gives ready access to the mare and foal immediately postpartum (after birth) but some mares resent confinement either due to the restricted space, or the lack of social interaction with other herd mates. A clean, grassy paddock would be ideal, but not every facility has this luxury. We should consider the experience and temperament of the mare. Maiden mares may need more supervision during the foaling process, while veteran moms can usually get this done without any help at all. If a stall is our only choice, try to find an environment where she is most at ease. If she paces the fence or stall, she is obviously not comfortable.

Some nervous mares respond well to having a buddy horse in a stall nearby. Finally, remember that millions of mares have given birth without people around to worry about them. So relax. Enjoy the miracle of your new foal.

* Reprinted with permission of the AAEP. To view the entire article please visit then click Horse owners, Ask the Vet