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January 27, 2021

The veterinary profession continues to learn about the long-term health effects of surgeries done to prevent unwanted canine pregnancies. These insights help Dog Moms and Dads make better decisions about when to spay or neuter dogs. Simply put, our goals must bridge both reproductive protection and long-term comfort and health for the dogs we love. Researchers from UC-Davis looked at associated joint disorders, cancers, and urinary incontinence in 35 dog breeds and offered insights on making this important decision. In some cases, the best option may be leaving some dogs intact. 


spay or neuter research page 1 showing the headline and first few paragraphs

Breed Differences: When to Spay or Neuter?

The answer to the big question is that it really depends on the dog, so NO single answer fits all breeds or ages. Also note that they refer to both surgeries as "neutering," so don't let that confuse you. They're talking about altering both female and male dogs when using that word. 

Researchers found "major breed differences in vulnerability to neutering, both with regard to joint disorders and cancers."

They also go on to explain their goals as follows: "The primary purpose was to offer readers some evidence-based information on breed-specific differences with vulnerability to neutering, including suggested guidelines for neutering ages to avoid increasing long-term health risks of neutering, if any. A secondary, unforeseen, purpose was to document breed-specific differences in the increases in some cancers associated with removal of gonadal hormones, as an area for possible research on genetic aspects of cancer occurrence."

Suggested Guidelines by Breed and Sex

The article includes a chart that shows several categories for suggested guidelines for when to spay or neuter dogs of different breeds, divided by sex. Their guidelines include these options:

  • Leave intact
  • Choice (which simply means "there was no increase risk [of joint disorders or cancers] for any age" of the breed / sex noted)
  • Beyond 6 months
  • Beyond 11 months
  • Beyond 23 months

For more of the 35 breeds considered, only 2 ended up listed as Leave Intact:

  1. Male doberman pinscher
  2. Female golden retriever
spay or neuter research recommendation chart showing recommended age of spay or neuter by breed and sex

Most of the breeds fell into the Choice category. Other breeds got classified with some benefit of waiting to spay or neuter dogs until they are over certain ages:

  • 6 months
  • 11 months
  • 23 months  

The recommendation to wait includes the breed most important to my current life --  border collies. Study authors from UC-Davis explain, "The suggested guideline for neutering, given the significant risk of cancers, is holding off neutering both sexes until beyond a year of age."

I'm happy to say that we did with both Clover and Tori. In hopes of solving Clover's non-stop UTIs as a puppy, we specifically allowed her to go through one heat cycle. Then, she was a LATE bloomer and went through a long false pregnancy, so she was about 17 months old when she was spayed. For Tori, we waited as long as we could for general health reasons. She literally went into her first heat right before her scheduled surgery -- around the 11 month mark (assuming we've guessed correctly at her likely birthdate). 

When to Spay or Neuter Your Dog -- See for Yourself

Here's the full list of breeds from the research so that you can see if yours was included. If not, maybe look at the most likely breeds in your mix or that are most like your dog and see what it says. Essentially, they chose the breeds that occur most frequently in the veterinary teaching hospital database + others needed to offer a sampling of both giant breeds and small breeds: 

  1. Australian Cattle Dog
  2. Australian Shepherd
  3. Beagle
  4. Bernese Mountain Dog
  5. Border Collie
  6. Boston Terrier
  7. Boxer
  8. Bulldog
  9. Cavalier King Charles Spaniel
  10. Chihuahua
  11. Cocker Spaniel
  12. Collie
  13. Corgi (Pembroke and Cardigan combined)
  14. Dachshund
  15. Doberman Pinscher
  16. English Springer Spaniel
  17. German Shepherd Dog
  18. Golden Retriever
  19. Great Dane
  20. Irish Wolfhound
  21. Jack Russell Terrier
  22. Labrador Retriever
  23. Maltese
  24. Miniature Schnauzer
  25. Pomeranian
  26. Poodle-Miniature
  27. Poodle-Standard
  28. Poodle-Toy
  29. Pug
  30. Rottweiler
  31. Saint Bernard
  32. Shetland Sheepdog
  33. Shih Tzu
  34. West Highland White Terrier
  35. Yorkshire Terrier

Find More More Details in the Supplemental Materials

In addition to the short sections in the main article for each breed, you can also access more detailed supplementary materials for each breed, which provides additional info such as:

Associated risks for joint disorders based on age of neutering:

  • Hip dysplasia
  • Cranial cruciate ligament rupture
  • Elbow dysplasia

Associated risks for each of these cancers or "at least one" of these cancers based on age of neutering:

  • Lymphoma
  • Mast cell tumor
  • Hemangiosarcoma
  • Osteosarcoma
spay or neuter research supplemental materials showing charts with risk of joint problems and cancers

Trending Which Way

I know top-level dog people who do not neuter their male dogs ever, feeling there is no medical benefit to doing so. 

Many top dog pals who have female dogs allow them to go through at least one heat cycle, feeling that it's better for their long-term health, even though doing so slightly increases the risk of mammary cancer in female dogs (about 8%, according to our internal med specialist). 

I'm sure there are people as well who never spay female dogs, but to me the risks are too great not to:

  • Unwanted pregnancies and puppies
  • Risk of mammary cancer, which is deadly
  • Risk of life-threatening uterine infection called pyometra

If you adopt your dog from a shelter or rescue group, you may NOT have a say in when to spay or neuter your dog. Their responsibilities and goals, even from a veterinary medical perspective, remain different from those of individual families.

I don't see that widely changing anytime soon ... though I'm incredibly thankful the rescue group from which we adopted Clover did not spay her at 15 weeks old and allowed me to make the best medical decision for her.

My Past Mistakes

Alas, I did not know better at the time in 2000, and I had our old boy Ginko neutered when he was like 6 months old. I believe to this day that's the reason he blew both knees -- cranial cruciate ligament rupture -- at the age of 3.

Quick other note ... We're seriously considering adding much more frequent video content to our YouTube Channel. We are galaxies away from hitting the stats required to make any advertising revenue over there, but if you could subscribe to our channel, it will help move us the right direction. 

See the video version of this same information below.

About the Author Roxanne Hawn

Trained as a traditional journalist and based in the Rocky Mountains of Colorado, USA, I'm a full-time freelance writer for magazines, websites, and private clients. My areas of specialty include everything in the lifestyles arena, including health and home, personal finance and other consumer interests, relationships and trends, people and business profiles ... and, of course, all things pet related.

I don't just love dogs. I need them in my life. Seriously.

  1. Medically, it’s better to spay your dog before their first heat. It greatly reduces the risk of mammary tumors. People who wait to spay their dogs until after their second heat greatly increase the risk of mammary tumors in their pets.

  2. Thanks for sharing this info! I didn’t learn that the early spay/neuter was a bad thing until I lost my best dog to Hemangiosarcoma at 8, which could have been part of a perfect storm related to his puppy neuter. I think that even vets are just learning that it’s best to wait. I am learning a lot about things you can do to support your pup’s health even when they have been spayed or neutered too early (as in the case with many rescues).

  3. Very interesting information in this blog, especially regarding all the difference amongs breeds/sex.
    It’s a tricky topic especially when you adopt from shelters, where they tend to do it as early as possible…
    Thanks for this article, I will share with my community!

  4. Hi, This article is truly wonderful, and it includes so much important information for dog lovers, thanks for sharing this useful article with us.

  5. Thanks for explaining that, for some dog breeds, it’s beneficial to wait to spay or neuter them for 6 months or more. My sister plans on buying a medium-sized breed puppy from a breeder this spring since she was finally able to find a pet-friendly apartment in her budget. I’ll have to save your article for later so I can reference it once she figures out what type of dog breed she’s getting.

  6. WOW! This info really turns things upside down and sideways, doesn’t it?! I’m not surprised to see female Golden Retrievers on the “leave intact” list. Both Callie and Shadow were spayed at 4 months. After 2 TPLO surgeries (17 months apart), we lost Callie to lymphoma at age 11. Shadow was luckier – she had some minor cruciate disease as she got older but no major issues until after her 14th birthday. We lost her to renal shutdown four months later. She was older, tired, and ready to reunite with her sister/best friend. Poor, sweet girl. I need to read the linked info re Corgis and male Goldens. I hate to think how young Ducky was when she was spayed at the shelter – she was only 7 months old when we adopted her and she had been spayed at least 3 months earlier. We are celebrating her 9th birthday today and she was diagnosed with dysplasia of her left hip last summer. Thankfully, it’s not so bad yet that we can’t manage the pain flare-ups. But I’m almost afraid to see what else she may be “in for”. Then there was Radar who we lost to heart worm disease, two months after we got him from the rescue. The poor boy had some muscle atrophy in his left hind leg as well. But he was sweet, happy, and loving right up to the end in spite of his health issues. We miss him terribly, just as we do the girls.

  7. This is wonderful information. I have been wrestling about when to say my now-three month old female Great Dane. I recently lost a rescue to fast growing,deadly mammary cancer. She was not spayed until I got her at six. I never want to have any dog, or me to through this. This info makes me more comfortable in waiting until she is 12- 18 months old and her growth plates have fused.

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