9 Nov

Should I Castrate My Dog? Castration does not reduce aggression in dogs

Neutering is the clinical term used to describe the surgical removal of the reproductive organs. In female dogs, the colloquial term is “spaying” and in male dogs “castration” - so this article applies to either!

The issue of neutering in dogs, particularly in male dogs, has remained a hot topic for many years. It is highly emotive and there was until recently a lot of contradicting information available. Although a lot of the unhelpful and incorrect information still exists, there is a very clear study by one of the world’s leading veterinary behaviourists, Dr. Ian Dunbar, that demonstrates clearly that castration should not be used as a magic wand treatment to cure reactive dogs.

The Science
Behavioural endocrinolgy is absolutely unique when it comes to both male and female canine reproduction and aggression. Castration has no direct effect on aggression but it does have indirect effects.

Castrating males makes them less of a threat to other males because in male dogs, testosterone production begins at approximately 18 weeks old as the dog enters adolescence. Where in all other mammals testosterone increases during adolescence to that of an adult male’s level and then remains so, in dogs it continues to increase to some five to eight times that of an adult male dog. The result is a dog that, to other dogs, smells like ‘hyper dog’. If the dog is castrated, they don’t pose so much of an apparent threat so they are hassled and attacked less and in turn, act less threatened and macho. Hence they’re involved in fewer dog fights.

However, unlike most other mammals, castration does not make them less aggressive. Perception is most likely the key here for those owners who report a reduction in reactivity. Castrated males still appear to perceive themselves as males and growl and act macho just as before, however, other males most likely perceive them as females and so act accordingly - the castrated males feel less threatened. Castration does cause dogs to roam less and it reduces the frequency of urination but we know it does not affect target or posture. Castration at birth slows down the onset of puberty but many of these males may hump, growl, fight and lift their legs when urinating.

Both procedures (castration and spaying) are permanent. They cannot ever be reversed so the behavioural results are there to stay. Think very, very carefully before neutering your dog and ensure you read this article fully.

Many owners castrate their dogs at around 10 to 18 months, believing it will stop the “aggressive” or “dominant” tendencies it is displaying. These behaviours are normal for dogs, particularly given that between 10 and 24 months, dogs experience a peak level of testosterone – hence the more boisterous and behaviour. Neutering the dog is all too often an uniformed decision and one too many dog owners sadly rush into due to a lack of information.

My position
To make my position clear, I’m not against neutering dogs, providing it is done for the correct reason, in the correct dogs and at the correct time in its life.

There are very recent alternatives to surgical neutering in the form of implants. The most recent advance is Suprelorin (manufactured and licenced by Virbac who I have no affiliation to or conflict of interest); a chemical implant lasting between 6 and 10 months, which suppresses the production of testosterone (it is only manufactured for the use in male dogs but there are tests being carried out for a female version).

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