Study: Slow-Releasing Deslorelin Delays Mares’ Heat Cycles

The drug used to bring mares into heat for breeding might be just as effective at keeping them out of heat when given at different doses.

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Austrian researchers found a slow-release deslorelin implant kept mares from coming into heat and exhibiting estrus-related behaviors. | Photo:
The drug used to bring mares into heat for breeding might be just as effective at keeping them out of heat when given at different doses, according to Austrian researchers.

Deslorelin, in the form of a slow-release implant, successfully keeps pony mares from having estrus behavior and coming into heat, said Christine Aurich, DVM, PhD, head of the Graf Lehndorff Institute, in Neustadt, Germany, and professor of artificial insemination and embryo transfer in the Vetmeduni veterinary school Department for Small Animals and Horses, in Vienna, Austria.

It’s the same pharmaceutical product as that used in the commercial drug Ovuplant, which stimulates ovulation within 48 hours for well-timed breeding, she said. But when veterinarians administer deslorelin at different doses over different periods, it can have opposite effects.

“Deslorelin is a GnRH agonist, which means it’s a drug that stimulates pituitary secretion and synthesis of the luteinizing hormone (LH) and follicle-stimulating hormone (FSH) gonadotrophins,” Aurich said. “In mares, LH stimulates ovulation and luteal function (creating a good environment for the embryo)

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Passionate about horses and science from the time she was riding her first Shetland Pony in Texas, Christa Lesté-Lasserre writes about scientific research that contributes to a better understanding of all equids. After undergrad studies in science, journalism, and literature, she received a master’s degree in creative writing. Now based in France, she aims to present the most fascinating aspect of equine science: the story it creates. Follow Lesté-Lasserre on Twitter @christalestelas.

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