Spay Or Neutering? When Does Science Say It’s The Right Time?

Jun 12, 2024

A research team from the University of California, Davis, has been diligently studying the best time to spay or neuter dogs. Spaying and neutering, in general, has been a hot topic among pet parents and those within the veterinary field; the perfect timing is what typically creates the most discussion. 

The team, led by Drs. Lynette and Benjamin Hart, also professors at the University of California, Davis, have recently updated their guidelines on when to neuter 40 popular dog breeds, based on their latest findings. Their new study, published in Frontiers in Veterinary Science, took into account both breed and sex and built on their 2013 research that found early neutering of golden retrievers increases their risk of joint diseases and certain cancers.

Their initial study sparked much debate about the best age to neuter other breeds. They’ve since examined over a decade of data from thousands of dogs treated at the UC Davis Veterinary Hospital to provide even more detailed information for dog parents.

They specifically looked at the correlation between neutering or spaying a dog before one year of age and the risk of developing certain cancers, including those of the lymph nodes, bones, blood vessels, or mast cells. They also examined the risk of joint disorders such as hip or elbow dysplasia and cranial cruciate ligament tears. These conditions are particularly concerning because neutering removes sex hormones that are crucial for processes like the closure of bone growth plates.Photo: A vet spays a dog on the operating table.

This most recent study focused on five breeds: German Shorthaired and Wirehaired Pointers, Mastiffs, Newfoundlands, Rhodesian Ridgebacks, and Siberian Huskies. They analyzed more than 200 cases for each breed from the UC Davis Veterinary Hospital’s records from January 2000 to December 2020.

They found that early neutering can increase the risk of joint diseases and certain cancers in some breeds. However, they also pointed out that the best age to spay or neuter can vary greatly depending on the individual dog.

The Harts emphasize the importance of personalized decisions regarding neutering, taking into account the dog’s breed, sex, and individual context. Their updated guidelines, which include a table reflecting research findings for all 40 breeds studied, can be found here.

The study suggests that health risks differ among breeds. For instance:

  • Both male and female Pointers had elevated joint disorders and increased cancers.
  • Male Mastiffs had higher rates of cranial cruciate ligament tears and lymphoma.
  • Female Newfoundlands had heightened risks for joint disorders.
  • Female Ridgebacks had increased risks for mast cell tumors with very early neutering.
  • Siberian Huskies showed no significant effects on joint disorders or cancers.

Professor Lynette Hart said that it’s always complicated to look at new paradigms in the veterinary field particularly since their updated guidelines tend to shift from the long-standing models in the U.S. and much of Europe, which advocate for early spaying and neutering.

Professor Benjamin Hart agreed, but also added that their guidance is to help give information and options for veterinarians to give to pet parents, who ultimately have the last word in deciding on their dog’s health and well-being. That’s why it’s important to see connections between early spay/neuter procedures with potential health concerns in mind. 

Their combined research studies will soon be available as a free e-book, Effective Options Regarding Spay or Neuter of Dogs, in the journal Frontiers of Veterinary Science.

In a perfect world, spaying or neutering after puberty would be beneficial. Think about your body developing without pretty major organs—it’s a significant change! However, we also recognize that in the world of dog rescue, things aren’t always so straightforward.

For rescue dogs, spaying and neutering early can be crucial. It helps control the pet population and ensures that more dogs find loving homes. The reality is, in shelters, there isn’t always the luxury to wait for the perfect timing. Spaying and neutering help prevent unwanted litters, which is vital for managing the number of dogs needing homes. 

And that’s why, ultimately, when it comes to the question of when to spay or neuter your dog, there’s no one-size-fits-all answer. The decision to spay or neuter, and when to do it, should really be made based on your dog’s breed, health, and personal circumstances.

In the end, whether you decide to spay or neuter early or wait until after puberty, what’s most important is that your decision is informed. We understand that deciding when to spay or neuter your dog is one of the most significant choices you’ll make for their health and well-being. It’s a topic that’s deeply personal and often filled with conflicting information. Hopefully, as more information about the science behind spaying and neutering comes out, pet parents will continue to feel informed and empowered. 

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