The 10th International Symposium on Equine Reproduction July 26-30 at the University of Kentucky was presented in four sessions: the non-pregnant mare, the stallion, conception and early development, and the pregnant mare and perinatology. Dale Paccamonti, DVM, Dipl. ACT, professor and head of the department of veterinary clinical sciences, school of veterinary medicine at Louisiana State University, recaps the non-pregnant mare session.

  • A number of papers examined the transitional period (between diestrus and regular estrous cycles) and ways to make mares cycle earlier in the year. A study from the labs of Xavier Donadeu, DVM, PhD, and Stephanie Schauer, PhD, et al. reported that administration of purified equine luteinizing hormone every 12 hours in early transitional mares stimulated the growth of follicles that could be induced to ovulate with the hormone human chorionic gonadotropin (hCG). A different approach was taken by Simon Staempfli, DVM, Dip ACT, Dip ABVP Equine, MRCVS, et al., in which mares in early and late spring transition were given a single dose of long-acting progesterone and found that while there was no effect on mares in early transition, 83% (10 out of 12) of mares treated in late transition ovulated within 10-24 days of treatment versus 25% (three out of 12) of nontreated mares. Further work with a larger number of mares will need to be performed to reaffirm this success.

  • Working with mares during the normal breeding season, David Beehan, DVM, examined serum progesterone levels after hCG treatment to determine if the levels could be used to predict ovulation. Mares receiving hCG had significantly higher progesterone 24 hours after ovulation than mares that did not receive hCG; however, these levels were not useful to predict ovulation.

  • A paper by Dominik Burger et al. examined mate choice by mares. Studies in mice and humans have demonstrated that mating preferences are influenced by the m