Suprelorin® (deslorelin acetate)
Suprelorin® is a subcutaneous implant designed to prevent fertility and suppress libido in male dogs for a minimum of six or twelve months, depending on the size of the implant (4.7 vs. 9.4mg, respectively). Developed by Peptech Animal Health, which was later purchased by Virbac Animal Health, Suprelorin has been approved for male dog contraception in Australia and New Zealand (4.7mg/six-month dose only) since 2007, and the European Union since 2008. The 4.7mg implant received regulatory approval in China and Mexico in 2019.
How does Suprelorin work? The implant, placed beneath the skin between the shoulders, releases a slow and continuous dose of deslorelin, a gonadotropin-releasing hormone (GnRH) analog. Deslorelin suppresses the reproductive endocrine system by preventing the production of pituitary hormones and testosterone, the male gonadal hormone.
So long as deslorelin is being released, the dog remains infertile and behaves as if castrated. (Note, however, that the manufacturer reports that it will generally take 2-3 weeks after implantation for testosterone to be reduced, and about 6 weeks to become infertile).
ACC&D believes that Suprelorin offers value for dogs who cannot safely undergo surgery, as well as for guardians who wish to prevent fertility without castrating (dogs can receive sequential implants) or are unsure about castration and want to “trial” a “castrated” dog. This might include, for example, persons who want to ensure that castration would not impact their dog’s working, herding, or hunting abilities. Numerous studies have found that the fertility suppression effect of Suprelorin is reversible, even after multiple (up to four) consecutive implants. Want to learn more about Suprelorin? Check out ACC&D’s resources below:
What about female dogs and the feline contingent, you ask? Although Suprelorin is only approved for male dogs, due to its mechanism of action, research has shown that deslorelin is effective at suppressing the fertility and hormone-driven behaviors of cats and female dogs, as well.
Thanks to an Emergency Drug Release, a Canadian veterinarian has been able to use and study Suprelorin in female dogs in select First Nations communities. Studies in cats have shown significant variability in duration of efficacy. A limited number of studies have found incidence of metropathies (uterine diseases, such as pyometra) in a portion of female dogs and cats treated with a Suprelorin implant; further research on this topic is needed.
Suprelorin mimics GnRH, which means it initially stimulates release of pituitary hormones and thus can induce estrus in female cats and dogs. Though very temporary and soon followed by long-term hormonal suppression, it is possible that animals could become pregnant during this estrus. These are both concerns that would need to be addressed in any use of Suprelorin in female animals.