Larry Catt, D.V.M.
Larry G. Martin, D.V.M.

24 Hour Emergency
El Cajon (619) 590-1991
Ramona (760) 789-6845

Mare Reproduction Q & A

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1. Do you recommend culturing maiden mares?
Generally speaking, no. If conformation of the vulva is normal and the mare is in good shape, we do not feel it necessary. Exceptions may include a mare in her teens.

2. Does my mare have to be in heat to take a culture?
It is preferable to culture a mare in heat when the cervix is open, but not absolutely necessary.

3. Are conception rates in horses as high as other animals like dogs and cats?
No. Of all domestic animals, horses have the lowest conception rates, with only 55-60% of those bred annually in the U.S. producing live foals. Conception rates approach 75%, but a small percentage of mares do not carry full term.

4. Do you recommend breeding on foal heat or do you prefer the 30 day heat?
We are very comfortable breeding a mare on foal heat assuming that delivery was normal and there was no retained placenta. However, we do recommend intra-uterine flushing to “clean” the environment prior to breeding.

5. When my mare is in heat, she is very obnoxious and does not perform well at horse shows. Do you recommend a synthetic progesterone like Regu-Mate to keep her out of heat?
We used to, but with the advent of the progesterone implants, we can achieve the same results with much less cost to the owner. However, we do not recommend implants for pregnant mares that are progesterone deficient. For those pregnant mares, we use Regu-Mate to maintain the pregnancy.

6. How soon after breeding do you recommend pregnancy examination?
From the last breeding date we recommend begin teasing at day 14-15 and pregnancy checking by ultrasound around day 16-18. The primary importance of ultrasounding is to confirm early pregnancy and rule out the presence of twins. If the mare is not pregnant, the ultrasound can detect the presence of thickened uterine walls consistent with infection, cysts present in the uterus; fluid present in the uterus, and possible ovarian abnormalities.

7. I want to breed my mare but cannot tell if she is in heat or not, and do not have a stallion to tease with. What can I do?
The most efficient course would be to place the mare on a synthetic progesterone called Regu-Mate orally for 10 days and then give a prostaglandin shot on day 11. The mare will then be in heat in 3-5 days following the injection. Then you can plan on taking the mare to the breeder 3-5 days after the injection. Another alternative would be to give the mare a prostaglandin shot and then she should be in heat in 3-5 days. The Regu-Mate primarily assures the mare coming into heat.