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Neutering my dog – is it always the right thing to do?

By Sophie Platt, BSc, BVSc, MRCVS


Neutering is a surgical procedure to remove the reproductive organs; the testicles in males (called ‘castration’), and the ovaries/uterus in females (called ‘spaying’). This prevents breeding and is a very common procedure for small animal vets in the UK.

Rescue centres are often bursting at the seams with stray or abandoned dogs, and preventing unwanted litters is a very wise thing to do. But have you ever considered what other effects neutering might have on your dog? Is it always the right thing to do?

This question, unfortunately, does not have a simple answer. The other benefits and risks of neutering are outlined here; these can be discussed in detail with your vet if you are considering neutering your dog.


Benefits of neutering


Managing sexual behaviour

If a female dog is not spayed, they will have seasons roughly every six months. Each season will typically last for two to three weeks, during which time they will bleed. As well as being messy and hard to manage in the house, bitches in season can get pregnant if mated so it’s wise to keep them on a lead in public places.

Without neutering, many male dogs will have a strong sex drive. This is completely natural, but it can lead to problems. They are more likely to run off on walks in search of a mate, and can show unwanted behaviours (i.e. humping), often of inappropriate objects and unwilling recipients!


Reduced risk of some benign prostatic diseases

Non-cancerous prostate conditions such as benign prostatic hyperplasia, prostatic infections and cysts seem to occur less in castrated male dogs.


Reduced risk of some cancers

Neutering obviously eliminates the chance of testicular, ovarian and uterine cancer as these organs are removed during the neutering surgery. No testicles = no testicular cancer. Simple!

However, the risk of developing breast (mammary) cancer in female dogs is also reduced hugely by spaying when young. If a bitch is spayed before her first season, the risk of her developing mammary tumours is almost 0%. The risk increases to about 8% if spayed after her first season, 26% after her second season, and spaying after her third season does not offer any protection compared to an unspayed bitch.


Prevents uterus infections (pyometra)

Pyometra is a life-threatening uterus infection that usually develops in older dogs who have had multiple seasons. The uterus can fill like a balloon with pus, making the dog critically ill. Emergency surgery can be done, but this is a high-risk operation and not all survive. The anaesthetic risk and the likelihood of complications is much greater with pyometra surgery compared to routine spaying when they are young and healthy.


Prevents false pregnancies

These usually develop about six to eight weeks after their season, when they would be preparing to give birth if they were pregnant. She will behave like she is expecting puppies: become quiet, go off her food, become possessive over belongings, and may even start to produce milk.

As well as being unsettling for the dog, false pregnancies can be hard to manage for the owner and are often mistaken for an illness. Medication from the vet can be needed to stop a false pregnancy, which is costly for the owner and may have side-effects for the dog.


Risks of neutering


Increased risk of urinary incontinence in females

Urinary incontinence (loss of bladder control) can happen in any dog but is much more common in older, spayed females. Some breeds particularly (e.g. the Old English Sheepdog, Doberman and Border Collie) are at higher risk of developing this condition, and the risk is higher still in those who are spayed. Life-long medication is needed from your vet to help manage this condition.


Increased risk of obesity

It is well accepted that dogs are more inclined to put on weight after they have been neutered. You should take measures to ensure your dog maintains a healthy weight throughout its life, and you may find that food needs to be cut down slightly after neutering to achieve this.


Increased risk of anxious/aggressive behaviours

The cause hasn’t been proven, but there is some evidence to suggest that aggressive and anxious behaviours are more common in neutered dogs, compared to un-neutered. Particularly in males, vets widely accept that castrating a dog prone to nervous aggression may make the problem worse.


Increased risk of some cancers

The risk of developing some types of cancer (such as lymphoma, mast cell tumours and prostate cancer) is increased in neutered dogs. The increase in risk here is slight, so must be kept in proportion.


Coat changes

After castration and spaying, a dog’s fur can become a little more fluffy and less shiny. This doesn’t cause any problem to them, it just affects the way they look.


Increased risk of orthopaedic problems

Recent research is highlighting a link between neutering and dogs developing orthopaedic problems such as hip dysplasia and cruciate ligament disease.


The risks and benefits of neutering dogs are complicated and will differ depending on your dog’s age, gender, breed, temperament, and underlying health. The reasons why neutering is linked to an increased risk of some diseases, and a reduction in others, are not fully understood and there is lots of research ongoing in this area.


Neutering is the right decision for most dogs, but when considering neutering your dog, you must consider them as an individual – is it best for them?

Sophie Platt, BSc, BVSc, MRCVS

Sophie completed a BSc degree in Animal Science at Nottingham Uni before going to Bristol Vet School as a mature student. She qualified as a vet in 2012, and after a short stint in mixed practice has been a small animal vet ever since. She currently works in a practice in Hampshire, and particularly enjoys internal medicine and diagnostic imaging. In addition to her clinical work, Sophie dabbles with some medical writing and loves the variety this brings. Away from work, Sophie has two young girls and a daft spaniel called Louie who loves walks on the beach. Together, her family enjoys water sports and trips in their campervan.

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