Pet Columns, Office of Public Engagement, College of Veterinary Medicine at the University of Illinois at Urbana-Champaign

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Caring for Your Pregnant Mare

Pet Column for the week of October 29, 2001

Office of Public Engagement
2001 S. Lincoln Ave.
Urbana, Illinois 61802
Phone: 217/333-2907
Jennifer Stone
Information Specialist

How you care for your mare need not change greatly when she becomes pregnant, but a few key steps will ensure that both the mare and the foal stay healthy.

Dr. R. Dean Scoggins, an equine Extension veterinarian at the University of Illinois College of Veterinary Medicine in Urbana, says "Assuming the mare is in good health and everything is normal, I would recommend not making any changes at all to diet or exercise for the first 4 to 5 months of the pregnancy."

In fact, a pregnant mare can be ridden up to the ninth month as long as no risky activities, such as racing or jumping, are pursued. It will not harm the fetus, and the mare will benefit from the exercise. Physical activity is safe because the foal remains fairly small until the last 2 to 2 months of pregnancy, at which time it doubles in size very quickly. Even late in pregnancy, the mare should be turned out so that she can get free exercise. This helps to offset problems that can occur with pregnancy, such as swollen legs.

It is important that the mare receive an adequate supply of minerals during pregnancy. This can be given via a commercial mineral mix containing 25 percent salt to increase the palatability of the mineral supplement. Dr. Scoggins says, "Don't feed another source of salt when using this supplement. The minerals don't taste very good by themselves, and horses tend to eat whatever tastes good to them, just like we do!"

It has been shown that mares that are plump tend to have fewer problems with pregnancy. On a body condition scale from 1 to 9 (where 1 is emaciated and 9 is very obese), it is best to have the mare at about 6 or 7 when she becomes pregnant.

Plumpness helps to offset the demands on the body not only during pregnancy but also during lactation and nursing. Lactating mares produce a huge amount of milk because foals nurse very frequently. If the mare is too thin during pregnancy, she may make it through the pregnancy but then not be able to produce enough milk for the foal.

Before breeding, the mare should be maintained on a regular vaccination schedule, but no vaccine should be given for the first 90 days of pregnancy to avoid any interference with the development of the fetus. In the 5th, 7th, and 9th month of pregnancy, a vaccine for rhino pneumonitis should be given. While this disease is not often a serious problem in adult horses, it can cause abortion in some pregnant mares. It causes respiratory distress in young horses and adults.

In the last 4 to 6 weeks before the foal is born, the mare can be given a routine booster for a variety of equine diseases. This causes the mare to make new antibodies for these diseases, which she will pass to the foal in the colostrum. Colostrum is an antibody-containing substance found in the milk of the mare during the first few hours of nursing. Antibodies passed to the foal in the colostrum help the foal stay healthy during the first months of life, while its own immune system has a chance to mature.

The mare should also be maintained on a regular schedule of deworming until the last month of pregnancy, when a daily wormer can be given. This daily wormer can be given until the foal stops nursing and dramatically reduces the incidence of parasitism not only in the mare but in the foal as well.

The owner of a pregnant mare should watch for overcrowding. The mare should not have to fight for feeder space. Also, hooves need attention during pregnancy. Since the foal can add a great deal of weight to the mare, problems may arise with break up and splaying of the hooves. For this reason the hooves should be kept in good condition and should be trimmed regularly.

Mares are fairly self-sufficient during pregnancy, but they do need some special care. A little extra effort can ensure a smooth pregnancy for both the mare and the foal. If you have any questions about your pregnant mare, please contact your local equine veterinarian.