Suprelorin Implants For Dogs

two chocolate labs

The Suprelorin implant for dogs is a capsule that placed under the skin and that slowly releases a hormone that affects your dog’s fertility. The Suprelorin implant for male dogs manages to mimic castration. It does this by impersonating the naturally occurring hormone gonadotropin.

Suprelorin initially increases your dog’s natural sex hormones. As a result the gland that usually produces becomes desensitised and stops producing them itself. As a result testosterone falls significantly, and your dog stops producing sperm.

Although not nearly as commonplace a treatment, the Suprelorin implant also has the potential to be used on female dogs. But the initial flare up caused by the deslorelin is a problem in female dogs because it brings them into season. So for the time being, this implant is almost exclusively for males.

The subject of castration presents a moral dilemma for many of us. Whether we’re trying to prevent unwanted pups, or moderate behavior, surgically removing a part of your dog can feel like a huge decision to make.

Recently, we’ve been presented with more options to solve this. Temporary and reversible contraception techniques have been becoming more commonplace. With treatments available that claim to produce the same results as castration, with none of the permanence and invasive surgical procedures.

Suprelorin Implants for Male or Female Dogs?

The hormone in Suprelorin affects both male and female dogs. Three potential uses for female dogs are induction of estrus.

In the short term, Suprelorin brings female dogs into season. It can also prevent contraception with prolonged use, and has been involved in the treatment of incontinence in spayed females. The most common target for the drug however, is adult male dogs as the implant renders male dogs temporarily infertile.

Uses of Suprelorin in Male Dogs

The Suprelorin implant is usually given to male dogs to prevent fertility or change behavior. At one time, castration was almost universally believed to improve a wide range of behaviors in male dogs. Including aggression which was thought to be linked to the hormone testosterone. However, only a third of castrated dogs showed any noticeable change in behavior for the better.

A number of recent studies have called into question the traditional views on castration reducing aggression. Some studies have even shown that castration may make aggression worse. It’s thought that this is because testosterone is a confidence building hormone. And much aggression in dogs is related to fear, rather than to alpha dog tendencies.

Suprelorin for dogs has the benefit of offering a test run to see how castration might affect your dog. One that can be done easily and before removing his testes surgically and permanently.

What is in Suprelorin for dogs?

The active ingredient in Suprelorin is deslorelin. This compound was originally marketed by a company called Peptech. But the most popular current product to use deslorelin is the Virbac superlorin implant.

How quickly does the Suprelorin implant work?

Deslorelin is released gradually into the dog’s blood stream as soon as the implant is placed under the skin. The contraceptive effect of the drug does not happen straight away. And the implant may need to be in place for 6 weeks before it’s fully effective.

A dog with an established Suprelorin implant is much less likely to try and mate. Due to the lack of testosterone. Even if this dog did mate successfully, the chance of it resulting in a pregnancy is incredibly low, due to the inhibited sperm production.

It’s worth pointing out though, that Suprelorin implants for dogs are not given to males before puberty. It’s not that it would necessarily harm them, although you would expect a lack of testosterone to have an effect on a male dog’s development, it’s just that we don’t really know what would happen.

How long will a Suprelorin implant last?

The length of time a Suprelorin implant will be effective for is determined by the dosage. As the implant steadily releases this contraceptive into the bloodstream, it only stops working when the supply runs out.

Your vet will discuss dosage based on how long you want the implant to affect your dog. A Suprelorin 4.7 mg implant for dogs, for example, will last about 6 months. If your dog receives a 9.4 mg implant, the length of time his testosterone will be inhibited will be 12 months. The 4.7mg implant seems to be more popular.

Over the course of 6 months you should get a pretty good idea of how your dogs behavior has changed.

Suprelorin implant side effects

Side effects are a fact of life, no matter what we’re trying to treat. Suprelorin is no different and we should be prepared and understand the potential risks. The most obvious side effects are the ones that would normally come from the act of castration. The resultant drop in testosterone could cause a change in your dog’s behavior. It might for example, result in a less confident dog. This loss of confidence can cause fearfulness or anxiety. Which in turn can result in a dog becoming stressed or aggressive.

Remember that ‘flare up’ we talked about as the initial effect of deslorelin. Well this happens in male dogs too. This means that Suprelorin has the potential to make your dog more fertile for a short period after implantation.

Other side effects

A 2012 study found that some of the dogs tested had a higher sperm count in the weeks leading up to the eventual decline. There is no evidence of an effect on your dogs fertility long term. You can expect fertility to return to normal after the implant has run it’s course.

Slight changes to your dogs appearance are possible as testosterone is a key factor in how the body generates and maintains muscle. The site of the implant will usually be rather sore for about two weeks. At this time inflammation can occur and the area might feel hard to the touch. This swelling can persist for up to three months, but should eventually go down.

If you’re concerned at all about the site of the implant not looking right, it never hurts to talk to your vet. Every dog will react differently, and some may have particular problems with the implant being under their skin.

Suprelorin implant cost

There are two main factors involved in the cost of Suprelorin for dogs; the actual cost of the implant, and the vets bills on top of it. Because of the amount these can vary country to country, state to state, and even clinic to clinic it’s very hard to make a reasonable estimate about how much you will pay.

In the UK prices can range from anywhere between £100 and £300, depending on the dose of the implant. And also on your own vet and how much they charge for their time. The figures in Australia are similar in AUD.

Suprelorin could end up saving you money.

Suprelorin Implant vs Neutering

Castration in male dogs is usually undertaken to both

  • Prevent reproduction
  • Improve behavior

Suprelorin can give you a glimpse into how neutering will affect their personality. This might not be something we even thought about if our main concern is limiting the potential to breed.

The Labrador Handbook by Pippa Mattinson(paid link)

If your dog lives with a female dog, and you don’t like the effect that the Suprelorin has on his personality, you may want to consider neutering your female instead. Surgical castration is an excellent and permanent way to prevent your dog making puppies. But we now know that it may be less effective at improving behavior. Results will vary from dog to dog. In a dog that is already showing signs of nervousness for example, an implant that causes a profound drop in his testosterone levels could potentially make matters worse.

What Suprelorin claims to deliver is the same results as castration, but with none of the permanence. With this implant we can in essence ‘test drive’ a castrated dog without needing to make the absolute decision. Using this method owners can decide whether the permanent solution is a good decision. It’s important to bear in mind that, with regards to the smaller dosage, these effects will only last 6 months.

All in all, Suprelorin appears to do what it says on the box. By temporarily stalling testosterone production, you get a dog that is infertile for a while. This gives you a chance to assess the dog’s behavior in the absense of testosterone.

Suprelorin for dogs - are these hormone implants right for your dog?

The Labrador Site Founder

Pippa Mattinson is the best selling author of The Happy Puppy Handbook, the Labrador Handbook, Choosing The Perfect Puppy, and Total Recall.

She is also the founder of the Gundog Trust and the Dogsnet Online Training Program 

Pippa's online training courses were launched in 2019 and you can find the latest course dates on the Dogsnet website


  1. My dog aged 3 1/2 years had the implant 12 months ago and will have a surgical castration later this month. I worked really hard with him over the past 12 months as he was really nervous and displayed reactive behaviour towards other dogs. He is so much better now and dogs can approach him without any reaction. I have noticed that as the implant is wearing off that he is marking territory what seems like every few seconds, he has also started trying to hump entire males again, and also getting really excited around my 4 year old grandaughter. I realise that the training will have to start all over again, personally I think the implant was a really good decision for us.

  2. My dog had the 6mth implant for behavioural problems when he was 2.5yrs old. He suddenly started humping any entire adult males and despite management (long lining) and intensive training it wasn’t getting better. We saw a veterinary behaviourist who recommended not castration because he is a rescue dog with low confidence around most dogs and she was concerned a sudden irreversible loss of hormones by castration could have been disastrous for him. The 6mth implant worked really well for the unwanted humping behaviour but he did become a bit more anxious around dogs that he did not know so ibwas really pleased he hadnt been castrated. However, soon after the 6mths elapsed I noticed his testicles growing, he began marking on walks much more and then he started approaching entire males dogs again wanting to hump them.
    I repeated the implant but decided to give him the 12mth version hoping that a longer time combined with lots of training would prevent the need to repeat.
    What has really surprised me is that after only 9mths his testicle are growing again, he is marking like crazy and starting to want to hump entire males again. So….. it has not worked as long (relatively) as the 6mth implant and its needs repeating again. I am going to speak to his veterinary behaviourist tomorrow but will probably elect for the 6mth implant.
    If he were to hump a male dog who really didn’t like it and attacked him, I fear that just one bad experience could turn him into an aggressively reactive dog. This might be very challenging to resolve so I’m desperate to prevent that. Management alone is very restrictive on our lives and one day I might just not react quickly enough to prevent him getting into trouble. So while I do not like the idea of repeatedly interfering with his natural hormonal state…. it is definitely the lesser evil than risking him becoming defensively aggressive.
    Has anyone else had experience of them not lasting as long as the data sheets say they should last?

  3. My 9 year-old dog had this implant 2 months ago because his testosterone was extremely high and caused him serious problems resulting in hair loss, sores and ruptures the full length of his tail. He was also put on long term antibiotics, so the treatment is being approached from antibiotic treatment and the Suprelorin implant. On day 7 after the implant was made he started cowering and clearly had lost every bit of confidence but that lasted for just half a day and after that he was just as confident as previous. The only difference to his personality is that he’s a little bit more co-operative so presumably not quite as Alpha male as before but this is hardly discernible. So for him the implant experience was all good.
    I understand from my vet that about a week after the implant has been made there is a brief surge of testosterone so his apparent lack of confidence in that time frame might have been that his testosterone had hit a temporary all time high and he was frightened by it.

  4. Hi. My Labrador has had a Suprelorin implant and it is my intention to have him castrated at the end of its effectiveness. My query is should I have him castrated whilst the implant is still active (and his testicles smaller), or wait until it has completely worn off and his testicles back to normal. I would prefer the former as his behaviour is so much better. Any advice would be welcome. Thanks

  5. Is there a way of getting the injection in the US. I’ve called quite a handful vets in Florida and they don’t offer anything but neutering. I don’t want to neuter my boys, I’ve complications with spaying and neutering with past Dobermans.

  6. My dog got suprelorin for prostata problems. He got depressed, after it stopt working he became hypersexual like he is in puberty. He is 9 years. Is this normale?

  7. My dog had the suprelorin implant and it worked fine. But now it has worn off he has overtly sexual behavior and it seems like he is having a testosterone surge all of the time. I had the dog 3 years before the implant and he barely ever showed this kind of testosterone fueled behavior which is why I opted for an implant to be sure he wasn’t going to be very affected. His libido is out of control now so not at all like it was before. Is this normal? How long might it continue? Is this a side effect? The makers of Suprelorin do not say so.

  8. Have you got any experience with treating benign prostatic hyperplasia with this chip? Is it recommended or should I castrate?

  9. My 2yr old american xl bully was dominant with other dogs becouse of this other dogs would attack him and then he would nail the dog so i had the 6 months supreolin inplant but he seem deppressed and has lost a lot of muscle mas even his head as shrunk is this normal and will it come back after the inplant has run its course

  10. My 8yr old Rottie boy had the implant to reduce his testosterone as the vet said this could be a contributing factor to his anal cancer. I did not want him castrated as I have his litter brother who was also entire in case this upset the balance between them. He was a very well balanced male with no issues and there was no change in his behaviour in general or with his brother or his brother with him. Sadly six months after the implant the cancer got the better of him and he had to be pts.

  11. I have a question,stay rests of the suprelorin in the body of my dog after the chip ist working not anymore?

  12. Lucy, there are no citations in the references section. Citations look like this:

    Neilson JC, Eckstein RA, Hart BL. “Effects of castration on problem behaviors in male dogs with reference to age and duration of behavior.” J Am Vet Med Assoc. 1997 Jul 15;211(2):180-2.

    I am not saying that to be a jerk. There are thousands of medical journals, and some (like JAVMA) have published thousands of issues. It’s very often necessary to have more information than you provided in your references section to track down a specific study that one is interested in reading.

    Finally, what you linked to in the text wasn’t “some studies” – it was a summary of a masters thesis. When the data that thesis was based on was analyzed by actual scientists the results were considerably different.

  13. “Some studies have even shown that castration may make aggression worse.” Could you please provide citations for these studies? I try to keep current on behavioral research but I am not aware of any such studies.

    Also, I very much wish that you provided actual citations for your references. It seems disingenuous that you don’t.

    • Hi Dan, You seem to have missed the references section at the bottom of the article – but I have now added a link directly into the text too so that the scientific paper is even easier to locate. Hope you find it interesting.

    • Our dog had the implant 3 days ago and has become aggressive towards male dogs , is this too soon for a testosterone surge post implant