People can now avail of non surgical techniques to control the fertility of their male dogs. An implant, Suprelorin, is available that reduces the fertility of the male dog for either 6 or 12 months depending on the strength of the implant.

Suprelorin is also used for male ferrets. Suprelorin is an implant that is is injected between the shoulder blades. It is a hormone implant containing a GnRH agonist analogue, which provides a flexible, reversible alternative to surgical castration. Once implantion is made there is an initial hyperproduction of sperm and after 6 – 8 weeks the sperm production is greatly reduced to a level of infertility. The active substance in Suprelorin, deslorelin, acts like the natural hormone gonadotropinreleasing hormone (GnRH) which controls the secretion of other hormones involved in fertility.

Suprelorin is given as an implant that slowly releases a continuous low dose of deslorelin. This suppresses (blocks) the production of follicle stimulating hormone (FSH) and luteinising hormone (LH). As a result in male dogs and ferrets less testosterone circulates in the blood, the dog and ferret stop producing sperm and its libido is reduced. If a dog or a ferret under treatment with Suprelorin were to mate with a female dog (“bitch”) or female ferret (“jill”) on heat, the chance of the bitch or jill becoming pregnant would be extremely low. All studies showed a reduction of testosterone levels in the blood, a reduction in the size of the testicles, decreased libido and decreased spermatogenesis (when fewer sperm are produced by the testicles). In more than 95% of dogs, these effects started at six weeks after implantation and between 5 and 14 weeks in treated ferrets after implantation. The majority of dogs regained normal semen characteristics approximately one year after the last treatment and dogs have been able to successfully mate with bitches, after treatment with Suprelorin was stopped.

The return to normal fertility after the end of the treatment has not been investigated in ferrets. Dogs can have some moderate swelling at the implant site in the two weeks after implantation. There can also some be some local reaction (e.g. inflammation, hardening) for up to three months after implantation. Any swelling or local reaction resolves naturally.

Ferrets can have transient moderate swelling, itching and redness at the implant site. Suprelorin is not recommended for use in dogs and ferrets that have not yet reached puberty, as it has not been investigated in these animals. The size of the testicles will decrease during treatment. The length of the infertility is dependent on the concentration of the implant and the return to sperm production is variable depending on the animal size.