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Should I Spay/Neuter My Dog?

Sophie Jackson is a dog lover and trainer living in the UK. She competes in agility and obedience with her four dogs.

Spaying or neutering your dog is the easiest way to avoided accidental pregnancies occurring

Spaying or neutering your dog is the easiest way to avoided accidental pregnancies occurring

Spaying or neutering our pets is the process of removing an animal's reproductive ability. There are several other terms that are used to refer to this process including castration (for male dogs only), de-sexing and fixing. However, the commonest veterinary terms are spay and neuter—spay referring to the removal of the female reproductive organs, and neuter referring to the removal of the male's testicles.

To confuse the situation, there are different types of spay/neuter and in the case of male dogs, there is even a version that is temporary.

There is also a lot of information out there that is misleading about whether it is safe to spay/neuter a dog, the best age to do so, and what health benefits it can have. All of these factors make deciding whether to spay or neuter our dogs a potentially confusing, even anxious, decision.

Intact dogs will roam looking for a mate if allowed

Intact dogs will roam looking for a mate if allowed

What Is Spaying?

A spay refers to the operation that removes either all or part of a female dog's reproductive organs.

In a traditional spay, which can be performed by your regular vet, the dog's uterus (where the puppies develop) and ovaries are removed completely. This prevents a dog from having seasons, becoming pregnant and suffering serious health problems such as pyometra.

The operation is performed through a small incision under general anesthetic, and the dog can usually return home the same day. Because of the nature of the surgery, the dog will need time to heal internally, even after the external scar is gone.

Laparoscopic Spay

A second form of spay is less commonly available and may require a visit to a specialist vet with the right equipment. It is called a laparoscopic spay or lap spay. This form of surgery only requires two miniature incisions as only the ovaries are removed.

Pros and Cons

The advantages of a lap spay are that it has a shorter recovery time, and the dog has less post-surgical pain. The disadvantages are that it is usually more expensive as it requires special equipmen,t and it is not always easy to find a vet who performs lap spays local to you.

Dogs may fight each other in the presence of a female in season

Dogs may fight each other in the presence of a female in season

What Is Neutering?

Neutering is the process of removing a male dog's testicles completely, or altering them in such a way they can no longer produce sperm.

The traditional and commonest form of neutering is where the dog's testicles are both removed under anesthetic. Healthy testicles are on the outside of a dog's body, so the process is far less invasive than spaying a female.

Occasionally, a dog may have a retained testicle, which means it is still inside the body cavity. Retained testicles always have to be removed surgically as they can cause serious health complications if left. The surgery for this is slightly more intensive due to the testicle being inside the dog.

Chemical Neuter

Another form of neutering is known as a chemical neuter. This is only a temporary neuter, lasting between 6 and 12 months, but it does render the male sterile and unable to reproduce (though this is not instantaneous). There are a couple of types of chemical neuter out there, but the one most often seen is an implant that is injected into the dog and which slowly releases chemicals that suppress the male hormones.

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Chemical neutering is handy for the short-term, but there is still debate about whether it is safe to use long-term and what other health risks may be associated with it.


An uncommon option for male neutering is a vasectomy. As in humans, this is a procedure that leaves the male intact but disables the tubes that carry the sperm. The dog therefore still has hormones, but cannot make a female dog pregnant. The procedure is simple, but not regularly performed.

Vasectomies mean a dog retains its sex drive, which is not agreeable to many owners. They also are still able to develop certain diseases which are prevented by a traditional neuter (testicular cancer, enlarged prostate), the combination of these factors make vasectomies an infrequent veterinary procedure.

Intact male dogs are more likely to scent mark

Intact male dogs are more likely to scent mark

The Benefits of Neutering/Spaying

Discussing the benefits of neutering and spaying is an important part of deciding if it is right for your dog. There are, however, many myths circulating about these benefits, such as that neutering an over-excitable male dog will calm him down. This is not true, dogs' personalities will remain the same after a spay/neuter, though their sex drive will be lower, if not entirely gone.

  • In females, spaying will remove the hormones that cause them to have a season. Most females experience behavioural changes during a season, some more severe than others. After a spay, they will no longer be susceptible to these behavioural changes or phantom pregnancies.
  • In male dogs, neutering will reduce their desire to roam in search of a female dog in season. Scent marking may also be reduced, however, if this behaviour has already developed it is likely a habit that will not magically go away when a dog is castrated. Similarly, humping behaviour is not necessarily removed when a dog is neutered and many 'fixed' male—and female—dogs will still hump toys, furniture, or other dogs.
  • Neutering can reduce some tensions among male dogs, if there is competition for a female, but this is again not a guarantee and some male dogs are more prone to being targeted and attacked by other dogs after they are neutered.
  • The biggest benefit from the perspective of managing the dog population is that neutering/spaying is an easy way to prevent unwanted puppies. It is a simple fact that there are more puppies born each year than there are homes for them, and rescues are regularly brimming over with dogs needing new homes. Reducing accidental pregnancies is one way of lowering the number of dogs in rescue.
  • It is understandable, therefore, why rescues encourage spaying and neutering. If you choose to keep your dog entire, whether male or female, you have a responsibility to ensure they do not produce unwanted puppies. This means ensuring that male dogs cannot roam freely to mate with females, and that female dogs are kept away from males during their season, which occurs roughly every six months. If you are not able to do this, it is best to have your dog spayed/neutered.
In homes with multiple dogs of different genders accidental pregnancies are more likely to occur if the dogs are intact

In homes with multiple dogs of different genders accidental pregnancies are more likely to occur if the dogs are intact

Health Benefits of Neutering Female Dogs

  • In female dogs, a traditional spay removes the womb and this makes it impossible for her to suffer from pyometra, a condition where the womb becomes infected. Pyometra is a serious condition that can affect a dog at any age and is fatal if not treated swiftly. Treatment typically means an emergency to remove the infected womb.
  • Age increases the risk of pyometra, with dogs aged between 7 and 8 seeming to be most at risk. A study in Sweden found that 25% of the intact female canine population would develop pyometra before the age of 10.
  • While there is a very rare form of pyometra that can occur in spayed dogs, for the majority of animals spaying will ensure they never develop the condition.
  • Spaying also reduces the risk of mammary cancer. This is cancer of the mammary glands (similar to breast cancer) and in 50% of cases is malignant (cancer that will spread without treatment). Over a quarter of unspayed female dogs will develop mammary cancers, this is significantly reduced when they are spayed. Though a spayed dog can still develop cancer.
  • There is varying evidence about the best time to spay to reduce the chances of mammary cancer. Spaying before the first season seems to almost eliminate the chance of mammary cancer, however, there are potential health problems from spaying this young that should be taken into consideration.
  • Other forms of cancer are reduced or eliminated by spaying, for instance, ovarian cancer. However, spaying will not stop all types of cancer.
Dogs that have been neutered cannot get certain types of cancer

Dogs that have been neutered cannot get certain types of cancer

Health Benefits in Male Dogs

  • The two main benefits for the health of male dogs with neutering are that it eliminates the possibility of testicular cancer and also prevents problems with the prostate gland.
  • Dogs that have either one or both testicles retained, (the testicle sits inside the body cavity instead of descending into the scrotum on the outside of the body) are more at risk of health complications and it is advised that these dogs are neutered sooner rather than later. They may be as much as ten times more likely to develop testicular cancer and there is also a risk of the retained testicle twisting on itself which causes severe abdominal pain and will require emergency surgery.
  • Testicular cancer is relatively common in dogs, with 27% of unneutered male dogs being at risk of developing it. Removing the testicles removes the risk of them developing this cancer.
  • Other health problems in unneutered dogs involve the prostate gland. This gland is influenced by the male sex hormones produced by the testicles. As intact dogs grow older the prostate can become enlarged, this causes issues with urinating and defecating. The prostate can become infected, causing a long-term fever. In rare cases, prostate cancer develops and this has a poor recovery outcome.
  • Nearly all issues with the prostate occur in unneutered dogs and neutering is often the first course of treatment in these situations.
Spaying or neutering a dog before it has reached puberty and finished growing can lead to joint disease in later life

Spaying or neutering a dog before it has reached puberty and finished growing can lead to joint disease in later life

Disadvantages of Spaying/Neutering Dogs

While the health benefits of neutering and spaying have been well researched, less interest has been shown in whether there are downsides to a dog's health from removing their sexual ability. This is gradually changing and recent studies have demonstrated that the biggest concern with neutering and spaying, is mainly due to when the age this is done.

  • Neutering or spaying a dog before it has reached puberty (generally under a year old) can have an impact on their joints. Hip dysplasia and cruciate ligament ruptures have been shown to be an increased risk in neutered/spayed dogs. This risk increases further if the dog is neutered under 6 months old. Both conditions are disabling and require either lifelong pain medication, or expensive surgery.
  • Other studies have shown that dogs may be at an increased risk of certain cancers when they have been neutered/spayed, with the age the dog was 'fixed' being considered a factor. This is a complex topic with some studies showing that early neutering/spaying seems to increase the risks of certain cancers, while other studies have found that spaying a female dog after the age of 12 months increased her risk of developing some cancers, compared to if she was spayed under 12 months.
  • The evidence for joint problems in dogs that are neutered before they are fully grown (particularly under 6 months) is more conclusive. A study done on golden retrievers and labradors found that the incidence of joint disorders increased by 4-5 times in dogs that were spayed or neutered younger than 6 months old.
  • This same study showed that dogs that were spayed/neutered before they had passed through puberty were taller than dogs spayed/neutered after puberty. This was because the hormones necessary to encourage the closure of the growth plates had been removed and the dogs' bones continued to grow for longer than they should. This was also believed to be the reason for an increase in joint problems.
  • Once dogs have passed through puberty and finished growing, neutering/spaying should not affect their joint health, which is why waiting until a dog is over a year old (older in large breeds) is important, and why in female dogs they should have a season before spaying.
  • Other disadvantages of spaying and neutering are more cosmetic. These can include weight gain, which is easily managed by controlling the diet, and changes to the coat quality, though not all dogs experience this and it is somewhat breed-dependent.
For most dog owners, spaying and neutering at an appropriate age is the best choice for a happy, long life

For most dog owners, spaying and neutering at an appropriate age is the best choice for a happy, long life

Should I Spay/Neuter My Dog?

As demonstrated above, there are a lot of conflicting considerations when looking at whether to have your dog 'fixed'. It should be noted that in general, if you have no intention of breeding your dog, then spaying and neutering is a good option, especially in girls where seasons can lead to hormonal problems and the risk of unwanted puppies. Here is a quick breakdown of the key facts.

  • Neutering/spaying prevents unwanted pregnancy
  • Female dogs come into season every six months and should not be walked around other dogs during the 3-4 weeks they are in season to avoid the risk of accidental mating.
  • Female dogs can suffer from pyometra or phantom pregnancies and have an increased risk of mammary cancer if left intact.
  • Male dogs can suffer testicular cancer and prostate disease if left intact.
  • Your dog's personality is not changed by spaying/neutering and it will not calm them down or remove unwanted behaviours (unless these are directly related to something like a phantom pregnancy).
  • Male dogs that have been neutered will still mark, some female dogs will do this also, even when spayed.
  • While some cancer risks are decreased or eliminated by spaying/neutering, others are increased.
  • Dogs should not be spayed/neutered younger than 6 months and preferably should be fully grown before being 'fixed' to avoid joint issues.
  • There is evidence that spaying/neutering increases the longevity of dogs, but this is also partly dependent on other factors, such as obesity.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.

© 2021 Sophie Jackson

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