Ask the Vet: Equine Reproduction – From the Stallion to the Foal

Answered by, Madison Seamans, DVM, MS, Kuna, ID. Courtesy of AAEP

Question: I bought an exceptional stallion 6 weeks ago, but he is cryptorchid with only his right testicle down. I heard that a surgical procedure could bring the crypt testicle down. Is it true that this can be done?

Answer: Cryptorchidism is the absence of one or both testicles in the scrotum. During embryonic development, the testicles are formed near the tissues that eventually become kidney, high in the abdominal cavit at about the level of the last ribs. In the mare, the ovary stays in that general area. In the boys, however, it travels down a long path known as the gubernaculum and arrives in the scrotum before birth. In the cryptorchid stallion, for some unknown reason, the journey was interrupted, and the retained testis is somewhere in the abdomen. The retained testicle is capable of making the hormone testosterone, so cryptorchid males will act like a stallion, even without testicles in their normal location. However, the heat in the abdominal cavity prevents the full development of the testicle so sperm cells cannot be produced. Due to their diminished size, these underdeveloped testicles can be very difficult to find.

If a retained testicle could be located surgically, it may be possible to pull it in to the desired location. There are also hormonal treatments available that have been effective in achieving this. However, some breed associations are very restrictive when in comes to cryptorchid stallions in their registry, so they should be contacted regarding their policy on this condition before any correction is attempted.


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.


Question: My 8-year-old mare has drooping udders. Is this normal? She is in with two older geldings.

Answer: During late pregnancy, the mammary glands undergo rapid expansion as the mare prepares to function as a dairy animal–making up to 4 gallons of milk per day to provide for the nutritional needs of the growing foal. After the foal is weaned, the teats in some mares do not shrink back to their original size. Since they are no longer producing milk, they may lack tone and appear to “droop”. This is relatively common and not considered abnormal.


Question: My dad has a foal that the mother will not accept after the foal was stuck in the mud. He has been bottle feeding it, but the foal has now developed scours. What can he do to help her?

Answer: Scours (diarrhea) in foals should be cause for concern and treated as an emergency. Although this can be a temporary response to stress, and being rejected by the mare certainly qualifies as a stressful event, it is also a sign of a life-threatening illness called neonatal septicemia. This foal should be seen by a veterinarian immediately. In addition, an equine veterinarian may be able to administer treatments to the mare to stimulate normal maternal behavior, so you won’t need to bottle feed the foal.