Pete the Vet: Is it okay not to neuter my pet?

The question this week is this: is it still “nicer to neuter” your pet?
Pete the Vet: Is it okay not to neuter my pet?

Pete the Vet: The question this week is this: is it still “nicer to neuter” your pet?

A few years ago, as part of a campaign run by Dogs Trust tackling canine overpopulation, I helped out by doing a voice-over on radio ads. I used a memorable catchphrase: “It’s nicer to neuter”, which was far more acceptable to male ears than “it’s cooler to castrate”.

The word “castration” upsets many men. The implication is the removal of masculinity, diminishing of power, and lessening of vitality. The word neutering is definitely nicer.

So the question this week is this: is it still “nicer to neuter”?

For cats, there is no question: castrated cats enjoy longer lives, a 90% reduction in fighting behaviour, and far fewer physical injuries. Urine spraying is also reduced, as is roaming behaviour. For all male cats apart from stud animals used for breeding, neutering at 4 – 6 months makes sense.

It’s more complex with dogs. Twenty years ago, neutering was believed to be beneficial for nearly all male dogs. And the resulting infertility played a useful role in reducing the population of unplanned puppies. Traditionally, roaming male farm collies have been implicated in accidental pregnancies across rural Ireland. However, the recent reduction in the number of unwanted dogs means that there is no longer a strong need for universal neutering of male dogs as a means of population control.

As discussed last week, female dogs, on average, live longer if they are spayed, because of the resulting reduction in serious illnesses. While neutering does prevent some serious illnesses in male dogs, overall there is no evidence that the procedure prolongs their lives. The impact of neutering on specific diseases is variable.

Testicular cancer is the most obvious disease that’s prevented by neutering: if there are no testicles, then there is no possibility of this. Testicular cancer is common: it’s seen in up to 25% of male dogs over the age of ten. However, in most cases, if testicular tumours develop, they are easy to identify (the testicle becomes visibly enlarged) and surgical removal (castration) at this stage is highly effective. Metastatic spread of the cancer to elsewhere in the body is rare, happening in less than 10% of cases. So the argument for castration solely to prevent testicular cancer is not a strong enough reason on its own.

Male hormones have a significant impact on diseases of the prostate gland, just as they do in humans. Benign prostatic hyperplasia is very common, causing enlargement of the prostate gland in 95% of older male dogs, and it’s prevented completely by neutering. However, most dogs that have this show no signs of unwellness at all, and if they do develop signs (such as difficulty passing urine or faeces), then neutering will produce a complete cure. So again, this disease does not necessitate early neutering. 

Strangely, neutering actually slightly increases the risk of malignant prostate cancer, but this is so rare that it’s not usually seen to be significant enough to impact on decision making.

Tumours under the tail – so-called perianal adenomas – are the fourth most common type of cancer to affect male dogs, and they are also stimulated by male hormones: the incidence is reduced by 90% by neutering. However again, they are usually benign, and neutering at the time of diagnosis is generally sufficient to stop their recurrence.

In recent years, better analysis of computerised data from veterinary practices has shown that there are some conditions in certain animals that may actually be made more common by neutering (and equally, there are some other conditions whose prevalence is decreased by neutering). However, in general, these impacts are small and irrelevant to most pets.

The most significant issue is obesity: neutered males, like spayed females, are 50% more likely to become overweight. In theory, this can easily be controlled by limiting a dog’s food intake and increasing exercise, but in practice, some owners find this difficult to achieve. In some breeds, like Labradors, that are prone to obesity, the challenge to attain life-long leanness can be made easier by choosing not to neuter.

Our understanding of the impact of neutering on male dog behaviour is the area where there has been the biggest change in recent years. Traditionally, this was one of the main reasons driving people to have their dogs neutered. Removal of male hormones causes a reduction in the male libido, leading to reduced straying of male dogs in search of females in season, reduced mounting of other animals (and people), and reduced urine marking. For many people, the removal of these anti-social behaviours is enough of a reason on its own for them to decide to neuter their pets.

In the past, male dogs have also been neutered in an attempt to reduce aggression or to make them calmer. Recent studies have cast doubt on this strategy. While it remains true that hormone-driven dog-to-dog aggression may be reduced by neutering, this is not the case for general liveliness or for other types of aggressive behaviour. For example, resource guarding (aggression linked to guarding food or toys) is more common in neutered males.

Most significantly, it’s now known that testosterone – the main male hormone – helps nervous or timid dogs to feel more confident, and since fear-based aggression is common, it makes sense to allow such animals to remain intact.

Finally, and surprisingly, as with female dogs, neutering some large breeds of dogs before sexual maturity (around 18 months) can increase the risk of certain orthopaedic problems, such as ruptured cruciate ligaments.

What should owners of male dogs do? Talk to your local vet. Every male dog should be assessed as an individual.

While it may be nicer to neuter some male dogs, it may sometimes be nice not to neuter others.

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