Ask the Vet: Equine Reproduction

From the Stallion to the Foal. Answered by, Madison Seamans, DVM, MS, Kuna, ID Courtesy of AAEP

Question: I have a horse that should be giving birth any day but today I noticed it looks like she has a lump on the back of her belly. Could it have anything to do with her milk production? Is this normal?

Answer: The presence of some swelling in front of the mammary glands is a common occurrence late in pregnancy. However, it is also common in mares with “a few extra pounds”. Although the appearance of a lump in this area is probably not a cause for alarm, you should have her checked by a veterinarian. A small percentage of mares that were pregnant the previous spring lost the foal sometime during the winter with no obvious signs. In anticipation of the new birth, the mare was fed liberally. The extra feed in the non-pregnant may have caused the extra fat deposits noted here today. Therefore, it would be good to know if the mare is still pregnant and the lump you noted is part of the normal process of mammary development.  Madison Seamans, DVM, MS, Kuna, ID

Question: I have a Thoroughbred mare that was bred and was ovulating from both ovaries. The veterinarian said that if she conceives twins, they will pinch one off. How safe is this procedure and how risky is it to the mare and remaining embryo? 

Answer: The presence of multiple follicles is normal during every heat cycle in mares. Multiple ovulation occurs during about 25% of cycles, though twin conceptions are much less frequent. Although it may seem like getting two foals for the price of one, twin pregnancy is not good, as it is a common cause of late term abortion. Even if the twins survive to term, the foals almost always suffer major complications, requiring extensive veterinary care and a poor prognosis.

An examination with ultrasound 14 days after breeding is the first step in helping the mare maintain a normal pregnancy to term. In the relatively uncommon event of twin pregnancies, ultrasound imaging allows us to reduce or “pinch” one of the embryos with minimal risk to the mare or the surviving embryo. Of course, all medical procedures involve some risk, and the location and age of the embryos will have some bearing on the treatment plan. However, this is a routine part of modern equine practice and the benefit far outweighs any potential harm to the mare. From a practical standpoint, a late term abortion of both fetuses is a distinct possibility and the mare will thus lose an entire year of productivity. With this in mind, early detection of equine pregnancy is an imperative part of good broodmare management.

Question: My gelding has a swollen sheath. His previous owner said this normally happens in the spring but he had no problems last spring. It gradually began swelling but now has become very swollen. He still continues to move around but seems somewhat more sore when moving last night, but still continues to run in the field. The area is not tender to touch. 

Answer: A swollen sheath is a very common presentation in equine practice. In most cases, a thorough cleaning will fix the problem, but the products available at the feed store will not always be sufficient. This usually requires sedation with products not available to unlicensed persons, so the horse will prolapse his penis and allow complete examination and cleaning. However, the cause of swelling in this area may be more complicated. Some deep-seated infections and even skin cancer can be found in these tissues. For this reason, a call to your local AAEP member is always a good idea. Your equine veterinarian will be able to examine, diagnose and provide the necessary treatments for this and other concerns you have about your horse.