How you care for your mare need not change greatly when she becomes pregnant but a few key steps will ensure that both mare and the foal stay healthy.
Assuming the mare is in good health and everything is normal, it is recommonended not to make any changes to diet or exercise for the fist four to five months of the pregnancy. In fact, a pregnant mare can be ridden up to the ninth month as long as no risk activities, such as racing or jumping, are persued. It will not harm the fetus, and the mare will benefit from the excercise. Physical activities is safe because the foal is fairly small until the last two to two months and a half of pregnancy, at which time it doubles size very quickly. Even late in preganancy, the mare should be turned out so the mare can get free excercise. 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 to increase the palatability of the mineral supplement.
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 emaciated adn 9 very obese), it is best to have the mare at about 6 or 7 when she becomes pregnant. Plumpness helps 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 nurs 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 to feed 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 the 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 four to six 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 antibody-containing substance are found in the milk of the mare during the first few hours of nursing. Antibodies passed to the foal in the colostrum helps the foal staying 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 owmer of a pregnant horse should watch for overcrowding. The mare shouldn't have to fight for feeder space. Also, hooves need attention during pregnancy. The foal can add a great deal of weight to the mare, problems may arise with 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 attention. A little extra efford can ensure a smooth pregnancy for both the mare and the foal.