Spay/Neuter Recommendations

Next month I’ll be speaking to veterinarians at the North American Veterinary Conference about, “Current Spay/Neuter Research: Tips for Counseling Your Clients.” I love this topic for a couple of reasons. Based on results of some relatively recent and compelling research, the veterinary profession must now question some of its long-held beliefs about neutering dogs. And, shaking up dogma within this profession is usually a really good thing.

Secondly, when it comes to neutering or any other medical or surgical issues, I’m a big believer in folks having the ability to act as informed medical advocates for their pets. Veterinarians play a super important role in facilitating this, and I am thrilled to have the opportunity to coach them on how to go about doing so.

Punching holes in neutering dogma

Here are a couple of examples of long-held beliefs related to neutering that my talk will call into question:

All dogs not being used for breeding should be neutered between four and six months of age.

By allowing dogs to reach sexual maturity before they are neutered (if indeed they are neutered at all), are there health benefits to be gained? Based on recent research data, this certainly appears to be the case for Golden Retrievers, Labradors, Rottweilers, Vizslas, and German Shepherds. Such breed-specific studies have documented that neutering before one year of age may increase the risk for development of behavioral problems, orthopedic diseases, urinary incontinence, and various types of cancers. Can and should this information be extrapolated to other dog breeds? We don’t know (yet).

Neutering prevents/eliminates aggression.

For decades, veterinarians in this country have been taught that neutering dogs prevents/eliminates aggressive behavior. While we know that castration definitely deters some undesirable male behaviors (urine marking, mounting, roaming), it does not pack nearly as mighty a punch when it comes to preventing or eliminating aggression, particularly that which is directed towards people. In other words, neutering is not the end-all, be-all for prevention or treatment of aggression.

What about female dogs? It’s been documented that aggression towards guardians can actually increase in dogs spayed before 12 months of age. And, in a study of Vizslas, the younger the age at the time of neutering the earlier the onset of aggression and other undesirable behaviors.

How veterinarians can counsel their clients

In my upcoming talk, my goal will be to provide veterinarians with tips on counseling their clients about if and when to neuter their dogs. (Unfortunately, I won’t have time to discuss the many options for “how” to neuter.). Here are the talking points I will recommend:

  1. What is the level of client responsibility? Will the dog be managed responsibly so as to prevent unintentional breeding? If not, neutering is a no-brainer. The pet overpopulation issue trumps all other considerations.
  1. What is the dog’s intended use? Will the dog’s occupation be breeding, showing, hunting, athletic competition, or simply couch surfing? If and when to neuter is, in part, determined by the dog’s intended purpose.
  1. An explanation of what we know and what we don’t know. I will provide the veterinarians in attendance with a current bibliography of spay/neuter research. This will hopefully enable them to talk to their clients about what we now know and don’t know with. Please contact me if you would like a copy of this bibliography.
  1. An explanation of the relationship between neutering and behavior. Before deciding when and whether or not to neuter, every client deserves an accurate understanding of the likely impacts of their decision on their dog’s behavior.
  1. Pick your poison! Be it pyometra, a torn cruciate ligament, hip dysplasia, behavioral issues, or cancer, we’ve all worked our way through significant medical and surgical issues with our beloved dogs. Such personal history definitely has a place in guiding decision-making about when, if, and how a personal pet should be neutered. See the example below.

A personal example

I will end my upcoming talk with a personal example involving Jacob, one of my children. When Jacob was in college, he fostered Tipper, a Hurricane Katrina rescue who was convalescing from heartworm disease. Tip was a gem, and the foster quickly turned into an adoption. This was Jake’s first dog independent of our family and, oh my, how he loved and cared for Tipper. He cared for Tipper through surgery and recovery for two torn cruciate ligaments. And, Jacob nursed his best buddy through his final months during which he finally succumbed to cancer.

Approximately six months after Tipper passed away, Jacob adopted an unneutered mixed breed puppy from a shelter in New Mexico. Fisher, as he came to be called, grew into an exuberant, loving, 65-pounder. Jake and I discussed when and if to neuter Fish. Based on his history with Tipper and recent research indicating that neutering before one year of age might predispose to cruciate ligament disease and/or cancer, Jacob opted to have Fisher neutered when he was approximately 18 months of age. Now, we will see what the future holds in store.

Food for thought

Are you aware that in some Scandinavian countries it is illegal to neuter dogs, and they have no animal shelters because there would be no animals to place there? I was shocked when I first learned of this, and it continues to blow my mind. This speaks volumes about the level of responsibility in caring for dogs there versus here in the United States.

More research about the impacts of neutering dogs is surely in the works, and I suspect that today’s neutering recommendations will be considered pure quackery a decade from now.

Clearly, there is no one-size-fits all in terms of if, when, and how dogs should be neutered. We must do away with the blanket recommendation that dogs be neutered between four and six months of age.

How do you weigh in on the topic of neutering dogs?

Best wishes,

Nancy Kay, DVM

Diplomate, American College of Veterinary Internal Medicine
Author of Speaking for Spot: Be the Advocate Your Dog Needs to Live a Happy, Healthy, Longer Life
Author of Your Dog’s Best Health: A Dozen Reasonable Things to Expect From Your Vet
Recipient, Leo K. Bustad Companion Animal Veterinarian of the Year Award
Recipient, American Animal Hospital Association Animal Welfare and Humane Ethics Award
Recipient, Dog Writers Association of America Award for Best Blog
Recipient, Eukanuba Canine Health Award
Recipient, AKC Club Publication Excellence Award
Become a Fan of Speaking for Spot on Facebook

Please visit to read excerpts from Speaking for Spot and Your Dog’s Best Health.   There you will also find “Advocacy Aids”- helpful health forms you can download and use for your own dog, and a collection of published articles on advocating for your pet’s health. Speaking for Spot and Your Dog’s Best Health are available at,, local bookstores, and your favorite online book seller.


Be Sociable, Share!

21 Comments on “Spay/Neuter Recommendations

  1. as a long time breeder and judge of bull terriers I now preach the mantra of no early s/n to all of my puppy buyers.most people who buy a pure bred dog are educated by the breeders. many of the “popular” breeds include mandatory castration in their contracts. I do just the opposite. I prefer that a breed like mine that is famous for bone and substance and bulk and power have all of the hormones they need to obtain optimal health. This does not mean I do not recommend castration at maturity. I do. But I find by that time many do not see a need for it in their males and some want to breed their females. I encourage showing ( my breed in 99% owner handled and we have a great time acting out in the ring to the chagrin of many judges) and that leads to breeding some of more worthy females. Thanks for this article. I have shared it in many places. Educating other vets will be a monumental chore but it can be done Thanks again

  2. I have been breeding Newfoundlands for over 40 years. For the first 25 no one neutered their males, and no one seemed to have any ortho problems other than the occasional HD as is seen in the breed. Also, no cancer reports. I only sell to reliable owners with fenced yards so indiscriminate breeding was never an issue. Then the push to neuter came along and became the politically/socially correct thing to do, and it was also given a big push by veterinarians. I soon began receiving reports of torn cruciates and some cancer, all in dogs that had been neutered, so I began to require my owners to keep their dogs in tact until at least 2 years of age. One of my owners is an administrative director at a major medical center overseeing several very large studies of the results of low and no testosterone in men – among other things, they have big problems maintaining muscle mass, and their tendons and ligaments become brittle, leading to ruptured achiles and other joint problems. After learning this, I now require no neutering at all for the life of the dog unless a specific case arises. When I explain this to prospective buyers, they are in full agreement, and I have not had any reports of cruciate tears since requiring this. Spaying is trickier in that the risk of pyometra exists, but I require owners to wait until at least one season, preferable 2 or 3, before spaying. Have had no reports of problems with complying with this requirement. I see this as a future problem for dog walkers or group boarding kennels that are popping up around here, but the health of the dog should be the primary concern.

  3. Years ago, I adopted a 7 year old champion basenji who had gone blind at the age of 2 due to detached retinas. He was a total sweetheart, and although I strongly believe in spay/neuter, I decided not to put him through any unnecessary medical procedure. So I left my “poor blind boy” intact. Five years later, when he was 11 years old, he developed testicular tumors and had to be castrated. Fortunately, he came through the surgery okay, but I had put his life at risk by delaying surgery until he was a senior. I discovered that prostate problems and testicular tumors are quite common in older male dogs, just like they’re common in humans. Surgical risk obviously increases with age. I’m sorry I waited until my boy’s life was threatened to do what I should have done as soon as I adopted him.

  4. We have 2 rescue dogs that we got as 8 week old puppies. Both were spayed just before being put up for adoption. While I understand the motivation behind their being spayed (not all we do so at a later date) I do have concerns for their health down the road (one is now 3 years and the other is 6 months). Obviously we had no choice and love the girls with all our hearts. The rescue groups here will not adopt out a dog without being spayed or neutered. But we have been through 3 ligament surgeries with past dogs among other major health issues so I have some concerns.

  5. I am so glad you give sound information about the neutering/spaying myth in canines. There is, sadly, so much confusion among dog owners regarding this issue! Owners have bought into the idea that neutering their dog will “improve” their behavior and lead to less agression which is totally false. I am a professional dog trainer, and having trained intact as well as neutered dogs, I have never seen a correlation between the neutering factor in agression. I also have noticed that spayed females hump a lot and neutered males mark no less than an intact male.

  6. What are the reasons you are thinking about neutering your two year old dog? As the saying goes, if it isn’t broke, why fix it?

  7. Wow! You’re right on cue Dr. Kay. I am seeking an OSS veterinarian for my puppy in the future. There is a FB page devoted to this topic with results/files tracking their dogs as they mature. Estrogen is vital in a female’s body and plays an important role in immunity.

    The little girl will also have a hernia repaired while she is under. Please keep us posted with notes from the convention?

    The Other Nancy

  8. I have been planning to neuter my dog when he turns two in March, but am having second thoughts. Thus far I have seen no problems with having him intact. He doesn’t mark. In fact, he still squats. He doesn’t hump my other dog, although he can sometimes be a bit too pushy with him. I’m not sure how he would be if I had him neutered. Might it make his behavior worse? I’ve had one aggressive dog and he was neutered at just over a year. He was aggressive both before and after neutering.

  9. continued…
    Bitches 3 and 4: both bitches were spayed post adolescence. One was lap spayed; the other was conventional spay. Both are healthy, although the conventional spay bitch has shown an unwelcome tendency to put on weight. In retrospect, I would have done the conventional as a lap spay. I would prefer to have done both using ovary sparing procedure but that was not available here at time of spay.

    Dog 5: Neutered as a very young puppy by previous owner. He has legs like stilts, and his body and head are completely disproportionate to his leg length. This dog cannot move correctly.

  10. Comment above continued…
    Dog 2: The risk of cancer, at age 7, began to concern me, so I elected to neuter my happy, confident, boisterous male. Post surgery, he suffered confidence issues, become fearful, and lost confidence, and he developed some inter-dog aggression issues. I also feel his structure broke down after surgery, possibly due to the obvious loss in muscularity attending testosterone production loss. It’s taken a lot of work to return his mental state to near where it was, and it has not recovered 100% 17 months post surgery. I believe these changes in behavior are directly related to the neuter.

  11. I am so pleased to see you are addressing this issue, Dr. Kay!!! Your balanced perspective adds value to the discussion. I think vets have an aggressively pro-neuter bias because in practice, they see the ugliest downsides of ineffective management… unwanted puppies, bad breeding outcomes, aggression development… I cannot imagine coming in to work every day and routinely dealing with that sadness. So, I agree it is critical and paramount to understand owner responsibility and reliability when considering how to advise clients.

    The role of hormones in a developing body is crucial and many faceted. The change of hormones at adolescence is a known cell signal for growth plate closure, regardless of species or breed, and this needs to be actively appreciated. It is probable the growth effects are magnified on larger breeds which are proportionally heavier and taller, but I believe the physical effects are similar regardless of breed. IMO, cancer oncogene signaling and control is most likely to have a breed dependency because the genes themselves have a breed dependency.

    IMHO, studies to date, both pro and con, are flawed. The studies showing improved temperament issues post-neuter are the worst. It’s hard to justify a true double blind study, though, because the end result of rigorous research is that study dogs will likely be PTS at the end and live a life of questionable quality up till then. As animal lovers, we have to work with the best data available and that which we can obtain without inflicting pointless suffering. We can also extrapolate the science from the far more rigorous molecular and cellular biology studies of human populations as well as adopt their study methodology (we don’t put humans to sleep at end of study!). We can do that if we are willing to abandon our mythological paradigms… and find funding.

    Reproductive hormones are important and we know this. IMO, denying a relationship between neutering and physical development is a “Flat Earth” point of view. As an instructor and competitor, I counsel responsible owners to avoid neuter until the growth plates close… if the owners are able to manage their dog appropriately. We would not harvest the reproductive organs of a human child to “control unwanted aggression” or “prevent unwanted births”… we would teach them appropriate behavior and employ management options. When it is feasible to do the same for dogs and their owners, we should take that approach.

    Cats? I have a slightly different opinion about that. 😀

  12. I think your blog is “right on”. Recently, we got a 5 month old intact male basset which was surrendered by a family who could not keep him. As members of the Golden Gate Basset Rescue, we jumped at the opportunity get have a new puppy in the house. Initially, we were a foster family and could not adopt him until after he had been neutered because this is a requirement of most county, if not all, animal shelters here in California.

    Since all of our previous bassets had been for show, we had no real experience for behavior of neutered young bassets as ours were all neutered much later – years later. However, since all of our bassets had very mellow personalities, we thought that this would continue with this new puppy who demonstrated a lovable, bubbly disposition. Therefore, following the requirements of the GGBR and local county protocols on neutering of all rescue animals as well as recommendation of our vet, we had him neutered at seven months so we could adopt him.

    Shortly, after he was neutered, we started noticing some behavioral changes. He started being suspicious of all strangers, possessive of “his things” like food dishes, etc, and biting no longer with the playful puppy like behavior, but with a bit of aggressive attitude.

    To counter this behavior, we have been working with him with more exercise, controlled social contacts with humans and other dogs alike, and with considerable TLC to give him alternatives to change his energy outlets. To date, we are noting significant results to date and happily can walk down the street with him at my side. Exercise with supervised play in a three acre playground seems to be the best solution at this time.

    Congratulation and best wishes for a successful briefing during the conference. I think we all hope to see more on this subject in the future. I also would like to see if the county animal shelters could be a bit more flexible on neutering. If we had seen your blog earlier, I assure you that he would not have been neutered before one year.

  13. Here’s the missing piece- people living in these countries are very responsible with their dogs. There is not any sort of pet overpopulation issue in spite of the fact that dogs there are not neutered.

  14. Dear Dr. Nancy,
    I read this ‘…Scandinavian countries it is illegal to neuter dogs, and they have no animal shelters because there would be no animals to place there?’, three or four times. I thought maybe it was a typo because it seems counterintuitive that if dogs are left unneautered there would be less dogs and no need for shelters. To me this is of course assuming animal shelter’s two primary functions are to spay/neuter (or oversee them) and also to temporarily house over population before adoption. Am I missing something? Grant

  15. Your article speaks volumes to what I have learned over the past 50 years of pet care, showing, breeding and rescue efforts made. Sadly local veterinarians insist on “early 6 month spay before the breasts develop”
    I would imagine this was a study of perhaps one breed. Breed specific spay/neuter should be taught as a preference to the old 3year lifetime a veterinarian experiences with a client. As an exhibiter, AKC did not accept neutered males to compete. However neuticles passed the judges inspection. Here again the neutered male never approaches male characteristics. Generally too refined or female stature is tell tale.
    Some terrier breeds are still great hunters but skin disease or seborrhea is all too common. Comparison
    tells the difference in litter mates that have not been neutered to those who have. Truly not enough study
    to breed specific and bloodline groups should or could show DNA tendencies. Thyroid imbalances have
    an important part even in early onset of cancer and off characteristics such as epilepsy in puppy spay/neuter.
    Policy of animal shelters demand very early 2 month surgery. Cats have a great deal to share with their urinary problems as well. Thank you for standing up for the health of our beloved companions.

  16. Dr. Kay – thank you for this blog. This is definitely a “hot topic” for discussion. My vet is in full support of waiting, and in fact, encouraged me to re-think my original plan to neuter my dog when he turned one. We are just past the one year mark and I will continue to monitor and evaluate things as we go along and if needed might neuter him further down the road. My new goal is to wait until he is two and fully grown so that he has had the benefits of the hormones during the first two years. Yes, he can be a bit obnoxious with his sometimes obsessive desire to hump all dogs he meets, but my previous dog (a female spayed at 8 weeks) also wanted to hump any dog that she met.

  17. Another good one and controversial as well; which is a good thing. It gets people thinking outside the box. Thanks Nancy, for once again, bringing critical thinking to the forefront so that we can be the best advocates we can be for our critters.

    I started my dog training career almost 40 years ago, after becoming a vet tech and working for a year. After my first year as a tech, it was clear that this wasn’t my calling but dog behavior was. I moved to France for a couple of years and began my training career there, professionally, that is. I am saying this because in Europe dogs are much more part of the family and ALLOWED in almost any public place; restaurants, theatres, stores, etc. Most of them are not neutered and these dogs are so much better behaved that our dogs here in the USA. If one walks into a restaurant, you’ll likely find a well mannered dog under 90% of the tables and I’d say the percentage of them that are fixed would be 10-20% if even that.

    Thanks again, for taking this to the veterinary community. I’ll share on my pages so doggie guardians know what to ask their veterinarian about with their new pups.

    Jill Breitner: Author of the Dog Decoder smartphone app

  18. Thanks for your comment Dr. Chapman. As I mentioned in my blog post, time was not going to allow me the opportunity to discuss the options of “how” dogs can be neutered. I wholeheartedly agree that it is time to consider other means of neutering, if a dog is neutered at all.

  19. Dear Dr. Kay, I think your blog is fabulous. However, we are doing dogs a big disservice by not considering vasectomy and hysterectomy (ovary sparing spay) as viable sterilization alternatives for dogs. These retain hormones while permanently sterilizing dogs and eliminating the risk of pyometra. There is considerable information regarding these procedures on the Parsemus Foundation website, and in the Files section of the Facebook group Ovary Sparing Spay and Vasectomy.

  20. Cookie was apparently spayed way young (based on our vet’s findings). She’s going to be five and she’s already paying for it. If I had the choice, I would not spay/neuter my dog(s) before they reach full maturity. Unfortunately, when adopting, one does not get much choice that way.

  21. I think vets must be very careful to respond to actual fact based research where spay/neuter and any particular medical condition is a cause and affect relationship and not merely a possible correlation. Most of the papers on the subject are very loose in keeping to the facts and ‘maybe’ becomes facts. Also many are merely retroactive compilations of data from clinic records where only two factors are considered – spay/neuter and any particular issue. These are in my opinion, extremely dangerous studies as far as making any responsible statements about the possible implications of spay/neuter at any particular age. Because the internet seems to be the education medium of choice for many owners and breeders, vets need to be the source of real facts as they are known, on the pros and cons of spay/neuter and age etc. and they need to be willing and able to discuss those with their clients.

Leave a Reply

Your email address will not be published. Required fields are marked *