How is chemical castration performed?

In a chemical castration, a small hormone implant is inserted under a dog's skin. The hormones cause the production of testosterone to decrease in the testicles after a number of weeks. A visible sign after a chemical castration is that the testicles decrease in size, they return in size as the effect wears off.

Is chemical castration permanent?

Unlike a surgical castration, the implant loses its effect after a while and the activity in the testicles starts again. This means the dog regains its normal testosterone level. For a long-lasting or lifelong result, you need to repeat the same procedure several times or let the dog undergo a surgical castration.

Why do chemical castration?

Chemical castration may be an option to reduce unwanted behaviours due to high testosterone levels. It could be, for example, that you have a male dog that is so fixated on female dogs and the smell gets them frustrated. In the case of chemical castration, this can decrease or completely subside, provided that the behaviour is due to testosterone and has no other underlying factors.

Behavioural problems such as male dog aggression and above all aggression towards people can rarely be remedied with either chemical or surgical castration.

Some choose to test chemical castration to see what effects it has before having surgical castration performed. Others only want to have an effect during certain periods or have the chance to change their mind. Regardless, it should always be done in consultation with a veterinarian. 

Sometimes a chemical castration can be done for various medical conditions where castration is part of the treatment but where, for various reasons, it is not suitable to put the dog to sleep and operate as with a surgical castration.

Advantages of chemical castration

Behavioural benefits of chemical castration in male dogs may vary between individuals. As the effect is reversible, if there is no effect on behaviour, your dog can go back to normal when it wear off.

Keep in mind that unwanted behaviours that are not solely caused by the testosterone will not disappear with castration. In these cases  castration needs to be combined with other measures such as behaviour training.

Side effects of chemical castration

Chemical castration is a minor procedure, but the dog can still have side effects. Some side effects are more common that others. In connection with the injection, some dogs may have a local reaction/swelling where the injection was made, but this passes over time. There is a significant risk of weight gain after chemical (and surgical) castration, so it's important to adapt feeding.

Changed fur quality can occur, often in the undercoat. In rare cases, the dog may develop urinary incontinence.

Certain tumour diseases are possibly more common in neutered dogs. Castration at an early age can increase the risk of certain joint diseases in large adult breeds.

In the weeks after the injection, the amount of testosterone in the dog increases. Not all dogs have problems with the temporarily increased testosterone levels, but some can, for example, become aggressive.

How long does a chemical castration last?

Hormonal implants are effective for approximately 6–12 months, depending on strength and individual variations. If you want to test chemical castration, it is recommended to start with implants with a shorter duration. If you choose to do the same treatment again when the effect has run out, you could then choose an implant with a longer effect.

How long does it take for chemical castration to work?

It takes approximately 6-8 weeks before the hormone implant gives full effect during a first treatment or if you have taken a break between treatments.

How much does chemical castration cost?

You'll need to discuss the cost of chemical castration with your vet. It can vary between different clinics and around the country.

Consult a veterinarian before deciding to have your male dog castrated and whether chemical or surgical castration is best suited in that case.