The implant is a tiny, waxy cylinder that sits under your dog’s skin. It is a prescription product that your vet will need to administer. Your vet will insert the implant under the skin between your dog’s shoulders in a simple process similar to microchipping. It is quick to administer and can be done in a consult, without leaving your dog for the day.
The implant contains a slow-release product that will resorb over time and does not require removal. After the implant is inserted it will release the active ingredient steadily over time. The active ingredient in the implant works by preventing the production and release of sex hormones, like testosterone, that are responsible for fertility; this results in decreased testosterone levels and infertility. This gives you and your dog the benefits of surgical castration without surgery or an anaesthetic.
Testosterone levels and fertility will gradually return to normal once the implant wears off. To maintain a state of lowered testosterone and infertility, a new implant is then inserted by your veterinarian at either six or 12 months depending on the concentration chosen for your pet’s individual needs.
Once your vet has administered the implant, the testosterone levels will reduce within 1-3 weeks and it will take 6 to 8 weeks for your dog to become infertile. This is because it takes time for the level of circulating testosterone to decrease after the implant is placed under your dog’s skin. The decrease in testosterone results in infertility. Because there is a natural lag between implantation and infertility, it is important for you to keep your male dog away from any females during the first 6-8 weeks after implantation, as pregnancy can still occur if they tie during this initial period.
The medical castration implant for dogs was created in the early 2000s by an Australian biotech company. And it is still made here in Sydney. It has been available for male dogs since 2005 in Australia and in Europe since 2007. It is now available as an alternative to surgical castration for dogs in more than 30 countries, giving pet parents more choice, depending on what is best for them and their pet.
The implant must be repeated every 6 or 12 months (depending on implant size) to maintain its effect.
The implant is biocompatible. That means it is not harmful or toxic to living tissue and because the active ingredient is very similar to the natural substance it is mimicking, there are no drug interactions or significant side effects.
The best age for desexing, including the use of this implant, will depend on what is best for you and your dog. This minimum age can be different for different breeds and is therefore something you will need to discuss with your vet.
There are no significant side effects with using the medical castration implant.
However, your dog’s testicles may decrease in size (by approximately 1/3) and may feel softer than normal. A decrease in testicle size is a good way to check if the implant is working.
Castration can be used to manage some behavioural problems in male dogs that may be linked to testosterone(behaviours such as humping, scent marking, and roaming) – and while these behaviours are normal dog behaviours, they can be excessive or unwanted. However, testosterone may not be the only cause of behavioural problems in male dogs and sometimes castration can have the opposite effect, making dogs more fearful and aggressive than before.
Medical castration is an alternative to permanent surgical castration that lets us test and see if lowered testosterone will work for your dog‘s unwanted behaviours. Medical castration is a reversible option with its effect wearing off over time, and your dog’s testosterone levels returning to normal, as a result of that. In contrast, surgical castration is permanent and doesn’t allow you to test this in your dog.
Unfortunately, it is not currently available for female dogs.