Managing Your Mare During Late Pregnancy

Most people who breed mares want their mare to foal at the beginning of the year. Mares are pregnant for 342 days, give or take 20 days, which means the mare is nearing late pregnancy in the fall. There are several things to consider as your mare enters her last trimester, especially her nutritional needs and vaccination status.

Most fetal growth will occur during the last trimester which will change your mare's nutritional requirements. Her need for protein, energy, calcium, phosphorus, and vitamin A will increase. A mare can gain over 250 pounds during her pregnancy. As her weight increases, her center of gravity will shift toward her rear. This shift will put additional strain on her abdominal muscles making exercise more difficult. During her last trimester, the mare should be allowed to get her exercise in the pasture or paddock rather than in a ring or on a track.

If your mare is on endophyte-infected tall fescue, she should be removed several months prior to foaling. Endophyte-infected tall fescue can cause a thickened placenta, prolonged gestation, retained placenta, lack of milk, and weak or stillborn foals.

Throughout your mare's pregnancy she should be on a regular vaccination, deworming, and hoof care schedule. Work with your veterinarian to determine the best protocol for your farm. It is recommended to make sure your mare is vaccinated for Eastern and Western encephalomyelitis, influenza, and rhinopneumonitis. Rhinopneumonitis can cause abortions in the last four months of pregnancy. Thirty-days prior to foaling, it is encouraged to get your mare vaccinated for Eastern and Western encephalomyelitis, influenza, and tetanus. These vaccines will provide protection for the newborn foal through the immunoglobulins in the colostrum. No dewormer should be given during the last 30 days of pregnancy.

Getting to the end of a mare's long pregnancy is fun and nerve wracking all at the same time. Being prepared and having a timeline of what to do when can help ease some of your anxiety. Remember to always consult with your veterinarian when it comes to vaccination and deworming protocols.