What's the best age to spay or neuter a dog?

March 14, 2023 - 3 min read
Border collie looking at camera, with his paw over his nose.

Unless they are destined to be part of a breeding program, most dogs should be spayed or neutered. Not only do these surgeries help manage pet overpopulation and the tragic euthanasia of dogs who can’t find homes, but they can also prevent serious health problems like mammary cancer in females and prostatic hyperplasia in males.

However, like any medical procedure, spaying and neutering both have upsides and downsides. In some dogs, performing the surgeries too early can actually increase the risk of certain types of joint disease, cancer, and other health problems. Getting the timing right is very important! Read on to learn when (and why) most dogs should be spayed or neutered.

Why is it important to neuter or spay your dog?

When a veterinarian spays a female dog, they usually remove both the ovaries and the uterus. Neutering a male dog involves the removal of both testicles. Let’s look at the benefits of both of these surgeries.

Benefits of spaying female dogs

  • Preventing unwanted litters

  • Avoiding dangers associated with whelping

  • Eliminating messy heat cycles

  • Preventing pyometra, a potentially fatal uterine infection

  • Reducing the risk of mammary (breast) cancer when spaying occurs early in life

  • Eliminating the risk of ovarian cancer

  • Reducing roaming

Benefits of neutering male dogs

  • Preventing unwanted litters

  • Eliminating the chance of testicular cancer

  • Reducing the risk of hyperplasia and infection of the prostate gland

  • Decreasing mounting, roaming, marking, and aggression

For the majority of dogs, the benefits of spaying or neutering outweigh any potential drawbacks. That said, it is important to acknowledge that no medical or surgical procedure is without some associated risks. For spays and neuters, this includes

  • Complications associated with surgery and anesthesia like infection, bleeding, and rarely, death

  • A greater chance of urinary incontinence in female dogs who are spayed early

  • For some large breeds, an increased risk of joint problems when dogs are spayed or neutered at a young age

  • An increased risk of certain types of cancer when dogs are spayed or neutered young

But to put these risks into perspective, a study published in 2013 found that, on average, spayed dogs lived 26% longer and neutered dogs lived 14% longer than individuals who were not spayed or neutered.

So, the question we need to ask isn’t usually whether to spay or neuter; it’s when to spay or neuter. Doing these surgeries at the right time can maximize their benefits and reduce their risks.

Is there a right or wrong age to spay or neuter my pet?

Traditionally, many dogs have been spayed or neutered before they were 6 months old, and for good reason! Performing these surgeries before most dogs reach puberty greatly reduces the chances that they could reproduce before being spayed or neutered. Also, when female dogs are spayed before their first heat cycle, they receive almost complete protection against mammary cancer. The lifetime risk of mammary cancer increases to around 26% after they go through two heat cycles or reach two and a half years of age.

But over the last few years, more evidence has been accumulating regarding the potential risks associated with early-age spays and neuters. Most research has been limited to just a few breeds. Thankfully, this prompted veterinary scientists at UC Davis to dive deeply into their college’s records and publish a more comprehensive study in 2020. Here are some of their paper’s key take-home messages:

  • No increase in joint disorders was noted in small-breed dogs who were spayed or neutered early.

  • Only two small breeds, Boston Terriers and Shi Tzus experienced an increased cancer risk when spayed or neutered early.

  • Therefore, the timing of these surgeries is most critical for large breed dogs and probably also for larger mixed breeds.

  • In only two cases, male Doberman Pinschers and female Golden Retrievers, do the paper’s guidelines include recommendations against spaying or neutering at any age.

For the rest of the breeds, recommendations for spaying or neutering fall into four categories:

  • choice – no increased risk at any age

  • beyond 6 months of age

  • beyond 11 months of age

  • beyond 23 months of age

Take a look at "Assisting Decision-Making on Age of Neutering for 35 Breeds of Dogs: Associated Joint Disorders, Cancers, and Urinary Incontinence" for more details.

Does pet insurance cover spays and neuters?

Generally, pet insurance companies will not cover a spay or neuter, as technically it is considered “elective.” That’s true at ManyPets as well. However, you might be surprised at just how much is covered in dog insurance plans, particularly if you add on an optional Wellness Plan.

Always consult your vet about spaying and neutering

Having all this information at your fingertips can feel overwhelming, particularly since every dog’s situation is unique.

How are pet parents supposed to balance an increased risk of one health problem against a decreased risk of another?

Talk to your veterinarian! Together, you can explore all the factors that are involved and determine the best time to spay or neuter your dog.

Jennifer Coates, DVM
Veterinarian, Veterinary Writer, Editor, and Consultant

Dr. Jennifer Coates is a writer, editor, and consultant with experience in veterinary medicine, science, animal welfare, conservation, and communications. She has written for outlets including petMD, Chewy, and ManyPets.