Benefits of Desexing Dogs

In several countries, including Australia, desexing your dog is considered an important part of being a responsible pet owner. In recent years there have been many studies into the effects of desexing a dog with respect to the risk of cancer or orthopaedic disease. These studies question whether a dog should be desexed at all and if so, the best age for them to undergo surgery. It can be challenging for an owner to work out what is right for their pet. Let’s explore the benefits of desexing dogs and what it means for you and your pet.

Before we go any further, it’s important to understand some of the limitations of these studies. Here are some questions to ask when you’re looking at whether the results of a study are as relevant as they appear.

  • How many animals were in the study? Were there enough individuals to draw a conclusion? An often-quoted paper published in 2020 by Hart et al (Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs; Associated Joint Disorders, Cancers, and Urinary Incontinence. Front. Vet. Sci, 07 July 2020) listed recommended ages of desexing for several breeds. However, many breeds only had a small number of animals in the study. For example, their research examined only 86 Irish Wolfhounds and 230 Australian Cattle Dogs. Can we assume the results of such a small study would be consistent if a much larger number of individuals were included?
  • Research into the benefits of desexing dogs of one breed may not apply to those of another. One North American study of Rottweilers found that dogs desexed before 12 months of age were more likely to develop a bone tumour than those left entire for longer. A similar examination of German Shepherd Dogs found no such effect. Genetics and breed play a role in the risk of an animal developing a disease, and this may have a bigger impact on their health than whether they are desexed or not.
  • The abovementioned study looked at medical records for dogs attending the Veterinary Teaching Hospital of the University of Davis California. These dogs may have different lifestyles, quality of nutrition and level of veterinary care to dogs that live in other less affluent parts of the world, all of which can influence the occurrence of some conditions.
  • Other factors unrelated to a dog’s reproductive status can play a role in whether a dog develops a disease. While early desexing in large dogs may influence bone growth and therefore the chance of them developing orthopaedic conditions, obesity is a huge risk factor for joint disease over and above any effect of desexing. Similarly, some studies show an increased risk of cancers in desexed animals of certain breeds but overall, the greatest risk factor for cancer in dogs is age.
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    The Benefits of Desexing Male Dogs Are Numerous

    Removal of a dog’s testicles not only makes them infertile, but it removes the main source of testosterone in their body. This has several positive effects on their health.

    The lack of testosterone in the body influences the health of the prostate gland. Benign prostatic hyperplasia is an enlargement of this gland which can interfere with a dog’s ability to urinate and defaecate. It is thought that 80% of undesexed male dogs have some degree of prostatic hyperplasia by five years of age.

    Prostatitis is inflammation of the prostate gland which can be painful and make a dog very unwell. Both conditions are less likely to occur in a desexed dog.

    With the testicles no longer present, the risk of testicular cancer is removed. This is particularly relevant to cryptorchid dogs where one or both testicles have not descended into the scrotum. These undescended testicles are at greater risk of becoming cancerous.

    Other conditions that have a reduced occurrence after desexing are perineal hernias and perianal tumours.

    Let’s not forget the behavioural benefits of desexing male dogs. Not all behaviours are influenced by testosterone but dogs without testicles do have reduced incidence of several unwelcome behaviours.

    • They are less likely to urine mark around the home and yard
    • They are less likely to show inappropriate mounting behaviour.
    • They are less likely to roam in the search for a female, so the chances of them getting lost or injured are reduced.
    • They may be less likely to fight with other male dogs.

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    Identifying the Benefits of Desexing Female Dogs

    Health benefits associated with the removal of the reproductive organs can also be seen in female dogs, and they are arguably more significant than in males.

    Desexing female dogs involves removing both ovaries and the uterus. The result is that the dog will not have heat cycles and will not become pregnant.

    Pregnancy and mothering can have adverse effects on a dog’s wellbeing. Pups can become stuck in the birth canal and the only way to deliver them safely is with an emergency caesarean. Toy breeds may develop low blood calcium when they are feeding their pups; this can cause seizures and requires urgent veterinary care.

    It is thought that as many as 24% of dogs will get pyometra before they are 10 years of age. Pyometra is a serious infection of the uterus. In many cases owners will notice a bloody or brown discharge from their dog’s vulva which will lead them to make an appointment with their vet. Some dogs will have a closed pyometra with no discharge. This is harder to recognise, and a dog may be very ill by the time they are diagnosed and treated. If a dog is desexed, there is no uterus so there can be no pyometra.


    Desexing female dogs also reduces the incidence of breast cancer later in life, but this protective effect is greatest if she is desexed before her first heat cycle. The older she is at the time of spay, the more time her mammary glands have been exposed to her hormones, and the result of postponement is that desexing will not reduce the risk of her developing this disease.

    There are some benefits of desexing dogs that apply to both males and females. It helps to reduce pet overpopulation by preventing unplanned litters. It can prevent dogs being given up to shelters because of bad behaviours associated with their hormones. It can control the incidence of hereditary diseases in a breed by preventing affected dogs reproducing.

    Benefits of Not Desexing Male Dogs Do Exist

    It is easy to understand that after reading about the advantages of desexing, a dog owner would be keen to make an appointment for surgery. There are still some valid reasons an owner may wish to leave their dog intact.

    Desexed male dogs have an increased risk of prostate cancer. This is not a common cancer, occurring in less than 1% of dogs but statistically it occurs in desexed dogs at twice the rate of intact dogs.

    Both male and female dogs show a change in their metabolic rate after desexing. On average, they need about 20% less energy after surgery. It’s easy to overlook this and continue to feed them the same as before, and the result is weight gain. This leads to medical issues such as degenerative joint disease, skin fold infections and a reduced lifespan. This is simple to manage but takes discipline – adjust the amount you feed your dog to keep them at a healthy body condition score.

    Get The Timing Right – There Are Benefits of Delaying Desexing of Dogs

    If you have decided that desexing is the best thing for your pet, the next question is when to plan the procedure. There is no rush. It may be appropriate to wait until your dog is older before booking that appointment with your vet.

    We have previously mentioned studies that explore the link between desexing and the risk of some cancers and orthopaedic diseases in dogs. Although there are limitations to the studies and we don’t have a lot of data, they do suggest that there may be an increased risk of these conditions in some breeds if desexed too early. For small breeds of dog, the age of desexing appears to have no effect on joint disorders and cancers. For other larger breeds, however, delaying desexing until physically mature may be beneficial.

    Early desexing may have an impact on a female dog’s urinary tract. Early desexing can result in a small immature vulva. It can then become buried under a fold of skin if she becomes overweight. The result is infection and urine scalding in that skin fold and an increased chance of urinary tract disease. Some studies show that urinary incontinence is more common in large breed dogs desexed at a younger age and delaying surgery until over 12 months of age may prevent this.

    There are also behavioural advantages to delaying desexing. A day in hospital will be particularly scary if your dog is nervous or anxious. There will be unfamiliar people caring for them, and strange smells and sounds. It may be appropriate to wait until they have undergone some behaviour modification and have developed more confidence before scheduling surgery.

    Although some studies suggest that delayed desexing or even not desexing reduces the risk of some cancers and joint diseases, there are other important factors that also affect this risk such as breed, environment, and individual genetics.

    When all is considered, there are many health and behavioural benefits of desexing dogs, and overall, desexed dogs live a longer and healthier life. The question about when to have surgery is one that should be discussed with your vet taking into account your individual dog’s breed and living conditions.

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