GnRH agonist (Histrelin acetate) on multiple ovulation in mare

Abstract

The horses have physiological reproductive particularies, presenting peculiarities in the follicular morphophysiology. The pharmacological manipulation of the estrous cycle in the mare is routinely used, since it presents high variation in the duration of estrus. In order to obtain higher conception rates, semen deposition in the female reproductive system should be performed close to the ovulatory period, with the use of only one inseminating dose. For this reason, drugs such as deslorelin acetate and histrelin acetate are used to induce ovulation, as well as multiple ovulations. The aim was to describe the pharmacological effect of histrelin acetate for multiple ovulations in mare. It was used a mare, Quarter Horse, five years old, located in a breeding center in the city of Nossa Senhora do Socorro-SE. For an oocyte ovulation induction was administred Histrelin acetate in the dose of 100 μg, performing evaluation of the reproductive system and monitoring the degree of endometrial edema, follicular diameter and its response to the inducing drug. Ultrasonographic analyzes were performed to identify follicular diameter, with subsequent administration of prostaglandin (PGF2α) to promote luteolysis of the last cycle. For the second cycle, histrelin acetate (100 μg/BID) was administered during five days. On the sixth day the same drug was administered with the first daily dose of (100 μg) and the second dose (250 μg) to induce multiple ovulations. It was concluded that the animal did not respond to the protocol established, believing it to be due to dose used and the start of administration when the follicles have with superior diameters, not demonstrating the expected pharmacological effect.