Castration – what, why and alternatives

What exactly is castration and why do we do it? In this video we look at the behavioural effects on dogs, and how we can use Suprelorin implants as a reversible alternative.


Hello everyone, I thought this week we’d talk about castration. It’s something that we do relatively commonly and is often a difficult subject to discuss, especially with men that bring their dogs in, for obvious reasons. But I just wanted to chat about what it is, what we’re trying to achieve with it. And what the alternatives are at the moment.

So, what is castration? Castration is removal of both the testicles, and it can be done in a few different ways, but the most common ways are making a little incision in the front of the scrotum and surgically removing the testicles through that incision- that’s called a pre-scrotal incision. The alternative would be to take the scrotum off with the testicles in them, and that’s called a scrotal ablation.

Now, in general most of the time we do pre-scrotal because it’s a much smaller incision, but in large dogs that would end up with a pendulous scrotum afterwards, we go for scrotal ablation to take it all away.

Taking the testicles away has two effects. The first thing is clearly sperm can’t be produced anymore, they can’t be released and ejaculated, and cause pregnancy. Worth noting though, a bit like having your tubes tied if you’re a man, it can take a certain amount of time for those spermatozoa to exit the body. Generally eight weeks, six to eight weeks is the quoted time where you just have to be a bit careful post operatively. There is a small chance it could cause a pregnancy up until that point. There might be still a few little sperms in there that need to come out.

The second effect of castration is that once the testicles are gone testosterone levels really plummet. Now, testosterone has lots and lots of effects. It causes beard growth, it causes males to have greater bone density, higher muscle strength, that kind of stuff. But one of the things it does do, is it drives secondary sexual behaviours. And in dogs we’re thinking about running off, cocking legs, humping activity, et cetera, et cetera. And one of the questions I quite commonly get asked is, “Will castration cure […] problem, a behavioural issue?”

In general castration will lower the drive to perform behaviour which is the secondary sexual behavior. Behaviour like running off, like cocking legs, can be helped by castration, or it certainly will reduce the drive for it. However, quite often we see these issues in older dogs where perhaps this behaviour has been going on for some time is that those neural pathways have really been laid in. And it can be really difficult … castration on its own isn’t going to break that. It’ll reduce the drive, but the patterns of behaviour may well still be there. There needs to be little bit of retraining as well for optimal effect.

With aggression and nervousness it’s all a little bit hazy. It potentially could help, it potentially could make things worse as well. Dogs which are really anxious, sometimes they seem to rely on a little bit of testosterone to give them that confidence to be out there. So, actually castrating anxious dogs might make them more anxious, and problem behaviours even worse.

So, I think you need to look at it very much on a case by case basis. It’s certainly not a panacea. One thing it will do is it will stop dogs from producing entire male dog pheromones. So, when they’re out and about they’re not going to be producing male dog pheromones, which means that other entire male dogs won’t recognize them as entire male dogs. And that may well reduce the challenge and negative reactions that your dog might have when he’s out and about on a walk.

So for anxious dogs, having other dogs not coming up to them and challenging them because they’re entire males, well they might feel more confident going out on walks after something like that. So, it’s very difficult to give a prediction on what the effects of castration are going to be. One thing I would say is earlier castration will reduce the development of secondary sexual behavioural problems. But earlier castration can give rise to long, leggy dogs, because it tends to delay the growth plate closure. And I’ve got an article on about about that.

So, what can we do then with these dogs when they’ve got an issue? We can’t really predict what the effect of surgery is going to be. Obviously once the testicles have been removed, there’s no putting them back afterwards. There is an alternative though, an implant called Suprelorin which basically causes chemical castration. It’s put in in exactly the same way as a microchip. There are two strengths, it lasts for either a minimum of six months or a minimum of 12 months. And essentially it will produce all the effects of surgical castration, but will wear off after some time. Usually with the lower strength, I would expect after 12 months it would start to wear off. And with the higher strength, after two years.

Suprelorin acts on the pituitary in the brain. The hypothalamus releases something called gonadotrophin releasing hormone. The hypothalamus in your brain releases this to the pituitary gland, and the pituitary then releases follicle stimulating hormone and luteinising hormone. Those are then released into the bloodstream and go to the gonads, either the ovaries or the testicles, and produces oestrogen or testosterone. So, essentially it’s hypothalamus GNRH to pituitary. Pituitary FSH and LH to the testicles.

Deslorelin, which is in Suprelorin is a GNRH analogue. It looks like GNRH, but it’s at really, really high levels, which is weird, because you’d think: doesn’t that just cause lots and lots of testosterone to be produced? Well, it does initially, so having the implant in will stimulate the pituitary to produce lots and lots of FSH and LH to begin with. So, there’ll be an initial spike in testosterone. But after a few days (the body’s always trying to get itself back in balance called homeostasis), the body down regulates these receptors in the brain. And so the secretion of FH and LH just falls off a cliff. And so the production of testosterone also falls off a cliff.

So, it’s pretty safe. In fact it’s very safe. The major side effect that we see is irritation, swelling, little bit of redness, erythema at the site of the implant. We’ve never seen anything worse than that. It’s obvious it’s working because the testicles really, really shrink down – they can shrink by 50%. You can tell when it’s starting to wear off, because they start to enlarge again

The implant itself, like I say, is the the size of a grain of rice. It goes in in a normal consultation, a bit like a microchip. And it’s biocompatible so after 12 months, or 24 months (when it’s wearing out) it’s all been reabsorbed, so there’s nothing left in the dog afterwards; and you can put another one in at that point.

So, essentially it’s a really good try before you buy. You can put the implant in to a dog, and you can observe what the effects on the behavior of that dog are as the testosterone levels go down. So, it’s a nice safety blanket for people who are a little bit unsure, or behaviourist who is trying to advise their clients on what the effect of Suprelorin, or the effect of reduced testosterone levels is going to be on that dog’s behaviour.

Usually eight weeks after implantation they’re infertile. There are a small number of dogs (in a study two in thirty) where it took 12 weeks. So, generally I recommend 12 weeks after implantation before you can be certain that there’s no sperms being produced, and testosterone levels are really low.

There you go, castration, like I say it’s an unpleasant subject. But it is something that we do see an awful lot of. And primarily it’s not a health issue, it’s more a social issue. So, I think we need to be fully informed. We’re taking healthy animals and we’re doing something to them for really our benefit. We need to make sure that we’re doing the minimum that’s required, and we’re doing it in a welfare friendly manner. Hope this helps, and I’ll see you all soon. Bye.

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