As discussed in our Available Products section, multiple countries have approved Suprelorin®
(manufactured by Virbac Animal Health) to provide long-term suppression of fertility and reduction of libido in male dogs.
What about female dogs and the feline contingent, you ask? Due to its mechanism of action, research has shown that deslorelin (the active ingredient in Suprelorin) is effective at suppressing the fertility and hormone-driven behaviors of cats and female dogs, as well. Though not yet approved for contracepting animals beyond male dogs, several studies have been undertaken to learn more about deslorelin as a contraceptive for cats and female dogs. Below are some key considerations based on data currently available, followed by links to learn more:
Efficacy and duration
Studies have found Suprelorin to be effective at contracepting cats of both sexes, as well as female dogs. One feline study used a 4.7mg implant (approved for minimum 6-month contraception in male dogs) and found significant variability in duration of efficacy. Male cats demonstrated 6 to 36 months contraception, with variable onset; females, 16 to 37 months.
A study with 102 owned female dogs found that one 4.7mg implant effectively contracepted animals for between 212 and 563 days, a duration that was extended with a second implant. Another study, organized by the nonprofit organization Foundation of Animal Wellness Initiatives, has employed Suprelorin to reduce unwanted births among free-roaming dogs in Canada’s First Nations communities. It has re-implanted dogs at intervals of 12-24 months, and these dogs have not become pregnant.
Although these findings are promising insofar as they show Suprelorin’s ability to offer long-term contraception (while offering reversibility), they also speak to the need for careful monitoring, or re-implantation at regular intervals, to ensure that animals will not regain fertility.
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.
It is, of course, possible that an animal could receive the Suprelorin implant while already pregnant, particularly within free-roaming populations. This occurred with six females in the Foundation of Animal Wellness Initiatives program. Each produced a normal litter with healthy pups, and they subsequently did not come into heat for 12-24 months.
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.
Are there ways to avoid this scenario? Good question! Introducing the implant during diestrus (right after estrus) has shown some promise in dogs; treatment of very young kittens has shown a significant delay in puberty without inducing estrus. Further research is warranted on this topic.
Learn more about Suprelorin studies for cats and female dogs with these resources:
ACC&D Suprelorin Product Profile and Position Paper
Contraception & Fertility Control in Dogs & Cats (ACC&D e-book)
ACC&D 6th International Symposium session "Lessons from the field: market acceptance and challenges"
ACC&D 5th International Symposium
ACC&D 4th International Symposium