Several reproductive specialists at Hagyard-Davidson-McGee veterinary firm in Lexington, Ky., are following about 100 pregnant mares. These are mares from farms which were either affected or unaffected by foal/fetal losses this spring; are 15 years old or younger; were bred March 15 or earlier; and are not going through the sales and will remain in Kentucky to foal next spring.

These mares will undergo ultrasound exams at least once a month until they foal, then vets will determine if there are any problems with the resulting foals.

Included in the ultrasound exams are studies of various anatomical features of the fetus that could indicate problems. So far, all fetuses have been normal. Some of the things being studied are width of chest, size of eye orbit, size of the aorta, and size of a femur. Starting at nine months gestation, ultrasounds will be used to measure placental thickness.

All of these exams will be videotaped for future study