This is the time of year when a majority of the foals in Oklahoma and the surrounding region are born. It is a season of great excitement and anticipation. However, it can also be a time of anxiety for the mare owner going through the foaling process for the first time.

The most important thing to recognize is that nature has developed a wonderful system of birth in the mare.

With the exception of Miniature horses and donkeys, mares usually do not have complications due to a foal that is too large because the uterus determines the size of the foal. Unlike cattle, mares have a lower occurrence of difficult deliveries. They can have, on occasion, mal-positioned foals or other complications.

The average length of pregnancy in the mare is 338-343 days. However, normal gestation can range from 320-380 days. Prolonged gestation is not generally associated with problems or extra large foals.

If a mare's pregnancy extends much past 360 days, a veterinarian should examine her to determine if she is still pregnant and confirm that all is well.

The viability of the unborn foal can be assessed with the use of ultrasound, just as with human babies. And the degree of fetal maturity can be assessed by checking calcium levels in the mare’s colostrum, the mare's first milk.

It is vitally important that the foal nurses colostrum within the first 12 hours of its life. Colostrum is extremely rich in antibodies that help prevent disease in the foal until its own immune system kicks in.

Without adequate amounts of colostrum, the foal is at an increased risk of infections. A veterinarian can test the colostrum to determine whether it is rich in antibodies.

Also, the foal's serum can be tested at 18-24 hours of age to evaluate IgG antibody levels. If IgG is inadequate, treatment should be instituted. Specially prepared serum can be given intravenously or a dose of colostrum from a tested resident mare could mean the difference for survival of that foal.

The OSU Center for Veterinary Medical Sciences has a 640 acre ranch located 10 miles west of the main campus. Activities at the ranch include the equine and bovine reproduction and barren mare programs. Both resident mares and client mares are foaled at the ranch.

The client mares range from the routine to high risk pregnancy mares and their foals. Fourth year veterinary students are assigned these mares as part of their training to become veterinarians. They monitor the mares during the late term of pregnancy by ultrasound and udder secretions to determine the onset of labor. As the mare’s delivery nears, she is placed on 24-hour observation until after her baby is safely born.

The mares and foals are closely monitored and if needed, are quickly transported to the Boren Veterinary Teaching Hospital for intensive care. This process is not only a client service, it provides students experience in all aspects of foaling mares and managing mares with foals.

The foaling program at the ranch, coupled with the neonatal intensive care unit within the Veterinary Hospital, has proven to be a very effective tool in training future veterinarians, as well as a valuable resource to the horse industry in Oklahoma.

Nature has provided an efficient system for the mare to deliver and care for her young. In those cases where an owner wants relief from the worry or when nature goes awry, the faculty, students and staff at Oklahoma State University can provide assistance and choices for the equine industry.

This column is provided by the faculty of the OSU Boren Veterinary Medical Teaching Hospital.

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