Breeders always appreciate ways to help improve their mares’ chances of becoming pregnant, and one way veterinarians can help is by administering prostaglandins. At the 2013 Society for Theriogenology Conference, held Aug. 7-10 in Louisville, Ky., Carlos R. F. Pinto, MedVet, PhD, Dipl. ACT, presented a lecture on using prostaglandin F_2? (PGF) to control the mare’s estrous cycle.

Pinto, an associate professor at the Ohio State University College of Veterinary Medicine, began by reviewing PGF and its effects on the mare’s reproductive cycle. PGF administration during diestrus (when the mare is not in heat) induces luteolysis, or the degradation of the corpus luteum (the structure formed after the follicle releases the egg, or ovulates, and then produces progesterone). Following luteolysis, mares will return to an ovulatory estrus, Pinto said.

Following PGF administration, Pinto said, there is generally "distinct evidence" (determined by checking concentrations of blood progesterone) of luteolysis within 24 hours; complete luteolysis typically occurs by 48 hours. Overt signs of estrus generally appear in three to four days, although they can appear in as little as two or as long as six days post-administration, he said