The administration of hormones to mares during breeding management is an essential tool for equine practitioners. Proper and timely administration of specific hormones to broodmares may be targeted to prevent reproductive disorders, to serve as an aid to treating reproductive disorders or hormonal imbalances, and to optimize reproductive efficiency, for example, through induction of estrus or ovulation.1
Gonadotropin releasing hormone (GnRH) is a naturally occurring decapeptide in mammals, including humans. The biologic action of GnRH (LHRH) is to stimulate the pituitary to release gonadotropins, especially luteinizing hormone (LH), but, also, follicle stimulating hormone (FSH). LH, in concert with FSH, stimulates ovarian follicular development; the LH surge ovulates the follicle.2
Histrelin is a synthetic GnRH used to promote ovulation in horses. It possesses similar clinical efficacy in inducing ovulation in horses as deslorelin or hCG, but differs from the natural decapeptide GnRH in two amino acid substitutions.
Histrelin is an even more potent GnRH analogue than deslorelin, but with similar clinical efficacy in inducing ovulation in horses as deslorelin or hCG. Histrelin differs from the natural decapeptide GnRH in two amino acid substitutions.1
Excepting very few examples of animals that proved to be allergic to histrelin, very few adverse effects have been reported. It is advised to call your veterinarian for medical advice about side effects regarding histrelin use in mares. In rare cases, irritation has been reported at injection sites 1. Once again, it is advisable to consult your veterinarian.
1Pinto, C., DVM. Hormones and Breeding, AAEP Proceedings, Reproductive Endocrinology, Vol. 59, 2013.