To neuter or not to neuter? Should I neuter my pet, and if so, when?

To neuter or not to neuter? Should I neuter my pet, and if so, when?

When it comes to cats, this is a simpler question, but for dogs it can be a little more complicated. We are going to look at the pros and cons of neutering/spaying in cats and dogs, and when is the best time to neuter.



When it comes to cats, there is not much of a neutering debate, as everyone pretty much agrees that neutering is the way to go. The only real downside to cat neutering is that neutered cats can gain weight more easily and should be fed a lighter food or slightly less overall to prevent weight gain. However, there are many benefits of neutering your cat, some of which are discussed below:

Trying to stop an unneutered female from mating can be very difficult – they will often just go into season over and over again until they mate, causing desperate behaviour in the female and a queue of vocal (and sometimes cat-aggressive) tomcats outside your house. If they do mate, then you have to care for the female through pregnancy, birth and rearing, and then you have unwanted kittens to deal with that all need good homes. (A female cat can have 30 kittens a year.)

Neutering male cats reduces their urge to roam and fight so they are less likely to go missing, get hit by cars, or get hurt. It also reduces their chances of catching FIV, an incurable disease which is spread during fights or mating. Unneutered male cats urine-mark your house and their territory with an unpleasant and pungent urine, and this is vastly reduced by neutering. Spaying female cats greatly reduces the risk of getting certain cancers, or an infection of the womb (called pyometra), both of which can be fatal. Pregnancy and birth also carry significant risks to a cat and spaying eliminates these risks.

A recent study found that on average, neutered males lived 62% longer than unneutered males and spayed female cats lived, on average, 39% longer than unneutered female cats. Also, very importantly, unwanted cats have to be put to sleep every year because there are too many unwanted animals and not enough homes for them, or due to complications from being left unneutered. You can help by getting your cat neutered. Vets recommend that neutering should be carried out before the kitten reaches sexual maturity, around 4-6 months old (with 4-5 months old being the optimum age), however this can be carried out at any age over 9 weeks old. Kittens should be kept indoors until they have been neutered.


The neutering debate is a little more complicated in dogs and has been the subject of many an argument between professionals. At the end of the day, studies have consistently found that neutered male dogs live, on average, 18% longer than their unneutered counterparts and spayed female dogs live, on average, 23% longer than unneutered females. However, it is not quite that simple, so let’s go through the pros and cons:


Unneutered males can get frustrated and can try to escape, putting them at greater risk of going missing or getting hit by a car. They are also both more likely to show aggression towards other dogs but also more likely to be the target of aggression from other dogs. Castration reduces the chances of certain cancers, prostate disease and hypersexual behaviour, eliminates the chance of getting testicular cancer and can help reduce aggression in some cases. Spaying females BEFORE the first season reduces the risk of getting mammary tumours drastically (the risk is still reduced if neutered after the first season but not by as much). Spaying eliminates the risk of unwanted pregnancies, ovarian tumours, womb infections (pyometra – very common in older unneutered females and potentially fatal), and phantom pregnancies.

Seasons in female dogs can both be messy and stressful and can attract unwanted attention from unneutered males. Unneutered dogs can be amorous towards people or objects, which can be a difficult behavioural issue. Also, if the female gets pregnant you then have to care for her during pregnancy, whelping and rearing (all of which carry their own risks) and with up to 12 puppies in a litter, that is a lot of work and potential expense, and a lot of good homes to find. Also, thousands of unwanted dogs are put to sleep every year because there aren’t enough homes for them. You can help by neutering your dog.


Neutering a dog does lower its calorie requirement, which means it will put on weight more easily and so should be fed a light food or a strict measured diet, with an exercise program in place. Neutering can also affect the texture and growth of a dog’s coat. Neutering can increase the risk of urinary incontinence in females when they are older, and in males, neutering may not reduce aggression or sexual behaviour once these have been shown.

Neutering has an effect on growth rate and maturation as well, and this is an especially important point in larger breeds. Neutering too early in large or giant breeds can cause skeletal development issues, joint issues, growth plate problems, and can increase the chances of certain bone cancers (only by 1% according to studies – but an increased risk is still an increased risk) later in life. Also, whilst neutering males does reduce the risks of certain prostate issues and diseases, it has recently been found to actually increase the risks of certain prostate cancers, whilst doing nothing to reduce the risks of other prostate cancers (prostate cancer risk was previously thought to be reduced by neutering, but it has recently been found to be more affected by genetics than neutering).

When to neuter your dog:

If you have a miniature or small breed, you can safely neuter from around 6 months, and medium breeds can be neutered from around 10-14 months old. Due to the effects on growth and maturation, neutering in large or giant breeds should not be carried out until the dog is fully grown – around 2-3 years old. This is a rough guide and should always be discussed with your vet before a decision is made (especially if there are other medical considerations to take into account.)

Gen Glass

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