Results of GnRH Agonist Implants in Oestrous Induction and Oestrous Suppression in Bitches and Queens

Abstract

Contents Over the last 10–15 years, long‐acting GnRH agonists have become widely available. In the field of small animal reproduction, most recent studies have focused on the use of two compounds developed under the form of subcutaneous implants: azagly‐nafarelin and deslorelin. Only the latter has been commercially available for use in male dogs, first in Australia and New Zealand, then in several countries of the European Union since 2008. Although officially marketed for male dogs, this compound has also been studied in bitches and more recently in queens. Some published papers or recent presentations at congresses – still unpublished – have focused on the use of GnRH agonists implants in females.

Use of cabergoline for oestrus induction in multiparous anoestrous Beagle bitches

“…The size of the litters was similar to that in our previous studies of Beagle breeding using the Ovulation Timing and Ovarian Assessment Test Kit. 15 It may be that deslorelin leads to a poor pregnancy and whelping rate compared with cabergoline. 14 Those authors reported that the whelping rate for early or mid-anoestrus bitches (at 80-160 days after the onset of proestrus) was 12.5% and the rate for late anoestrus bitches (at 200-590 days) was 65.2%.…”

Investigational hormone receptor agonists as ongoing female contraception: a focus on selective progesterone receptor modulators in early clinical development

“…GnRH agonists have been used for years to control uterine bleeding, to starve endometriotic implants of estrogen stimulation, and to shrink uterine volume in uteri with leiomyoma. GnRH agonists have been utilized as contraceptives in a wide array of different animal species for both female and male animals [6][7][8][9][10][11][12][13][14][15][16]. More recently, an attempt was made to utilize GnRH agonists delivered through an ethylene vinyl-acetate (EVA) vaginal ring in combination with physiologic doses of sex steroids added back for contraception [NCT 00706784].…”

Suppression of Fertility in Adult Dogs

“…In two studies, deslorelin was effective up to 27 months Sung et al 2006). In another study, still under investigation (Maenhoudt et al 2012), adult bitches treated only once with a 4.7 mg deslorelin implant returned to cyclicity 10.2 AE 5.1 months (2.1-23.3 months) after implantation. The stage of the cycle has no impact on the duration of oestrous suppression after implantation .…”

“…Good fertility rates post‐implantation are to be expected according to Maenhoudt et al. (). In a small trial, all the bitches were pregnant after breeding and the ones allowed to term were able to give birth naturally, with no sign of hypoluteoidism during pregnancy.…”