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Dr. Rob

I would like to share an article with you that summarizes the findings of a UC Davis study that shows just some of the many bad side effects from neutering, particularly early neutering.

Golden retriever study suggests neutering affects dog health

February 13, 2013

golden retriever dog(Photo courtesy of Hiroki Nakamura)

Neutering, and the age at which a dog is neutered, may affect the animal’s risk for developing certain cancers and joint diseases, according to a new study of golden retrievers by a team of researchers at the University of California, Davis.

The study, which examined the health records of 759 golden retrievers, found a surprising doubling of hip dysplasia among male dogs neutered before one year of age. This and other results will be published today (Feb. 13) in the online scientific journal PLOS ONE.

“The study results indicate that dog owners and service-dog trainers should carefully consider when to have their male or female dogs neutered,” said lead investigator Benjamin Hart, a distinguished professor emeritus in the UC Davis School of Veterinary Medicine.

“It is important to remember, however, that because different dog breeds have different vulnerabilities to various diseases, the effects of early and late neutering also may vary from breed to breed,” he said.

While results of the new study are revealing, Hart said the relationship between neutering and disease-risk remains a complex issue. For example, the increased incidence of joint diseases among early-neutered dogs is likely a combination of the effect of neutering on the young dog’s growth plates as well as the increase in weight on the joints that is commonly seen in neutered dogs.

Dog owners in the United States are overwhelmingly choosing to neuter their dogs, in large part to prevent pet overpopulation or avoid unwanted behaviors. In the U.S., surgical neutering — known as spaying in females — is usually done when the dog is less than one year old.

In Europe, however, neutering is generally avoided by owners and trainers and not promoted by animal health authorities, Hart said.

During the past decade, some studies have indicated that neutering can have several adverse health effects for certain dog breeds. Those studies examined individual diseases using data drawn from one breed or pooled from several breeds.

Against that backdrop, Hart and colleagues launched their study, using a single hospital database. The study was designed to examine the effects of neutering on the risks of several diseases in the same breed, distinguishing between males and females and between early or late neutering and non-neutering.

The researchers chose to focus on the golden retriever because it is one of the most popular breeds in the U.S. and Europe and is vulnerable to various cancers and joint disorders. The breed also is favored for work as a service dog.

The research team reviewed the records of female and male golden retrievers, ranging in age from 1 to 8 years, that had been examined at UC Davis’ William R. Pritchard Veterinary Medical Teaching Hospital for two joint disorders and three cancers: hip dysplasia, cranial cruciate ligament tear, lymphosarcoma, hemangiosarcoma and mast cell tumor. The dogs were classified as intact (not neutered), neutered early (before 12 months age), or neutered late (at or after 12 months age).

Joint disorders and cancers are of particular interest because neutering removes the male dog’s testes and the female’s ovaries, interrupting production of certain hormones that play key roles in important body processes such as closure of bone growth plates, and regulation of the estrous cycle in female dogs.

The study revealed that, for all five diseases analyzed, the disease rates were significantly higher in both males and females that were neutered either early or late compared with intact (non-neutered) dogs.

Specifically, early neutering was associated with an increase in the occurrence of hip dysplasia, cranial cruciate ligament tear and lymphosarcoma in males and of cranial cruciate ligament tear in females. Late neutering was associated with the subsequent occurrence of mast cell tumors and hemangiosarcoma in females.

In most areas, the findings of this study were consistent with earlier studies, suggesting similar increases in disease risks. The new study, however, was the first to specifically report an increased risk of late neutering for mast cell tumors and hemangiosarcoma.

Furthermore, the new study showed a surprising 100 percent increase, or doubling, of the incidence of hip dysplasia among early-neutered males. Earlier studies had reported a 17 percent increase among all neutered dogs compared to all non-neutered dogs, indicating the importance of the new study in making gender and age-of-neutering comparisons.

Other researchers on this UC Davis study were: Gretel Torres de la Riva, Thomas Farver and Lynette Hart, School of Veterinary Medicine; Anita Oberbauer, Department of Animal Science; Locksley Messam, Department of Public Health Sciences; and Neil Willits, Department of Statistics.

About UC Davis

For more than 100 years, UC Davis has engaged in teaching, research and public service that matter to California and transform the world. Located close to the state capital, UC Davis has more than 33,000 students, more than 2,500 faculty and more than 21,000 staff, an annual research budget of nearly $750 million, a comprehensive health system and 13 specialized research centers. The university offers interdisciplinary graduate study and more than 100 undergraduate majors in four colleges — Agricultural and Environmental Sciences, Biological Sciences, Engineering, and Letters and Science. It also houses six professional schools — Education, Law, Management, Medicine, Veterinary Medicine and the Betty Irene Moore School of Nursing.

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  1. Angela says:

    Paradigm shift. I wonder how this will be met on the rescue front.

  2. Angela says:

    It is a complete paradigm shift. I am curious how rescues will handle this, or if they acknowledge it at all.

    • Angry Vet says:

      they won’t

      • Mary says:

        Don’t be so quick to jump to conclusions. I do rescue, and I don’t scream “spay and neuter” at everyone. I believe that is an individual choice. But, rescues and shelters are also required to adhear to local and state laws. My county requires that all dogs adopted from shelters or rescues be altered before reaching sexual maturity (or 6 months of age). The last litter of puppies that I adopted out, I put a condition in my contract that said that the adopter would alter the dog before 6 months of age (to abide by my county regulations). But, I explained to them that the decision to alter their dogs was up to them, but my “official” requirement was to alter before sexual maturity. So, be careful where you place the blame for high rates of spays and neuters. It’s not necessarily the rescuers as it is the same folks who like to institute BSL, as if is the answer to aggressive dogs.

  3. susan says:

    so does this mean we shouldnt neuter male dogs at all? i have a year old intact male tervuren, i am holding off but it is very hard with this hellacious adolescent…breeder said wait till 18 months–i know many keep dogs intact…

    • Angry Vet says:

      see my article on behavior. Don’t rush to neuter

      • Oldlongdog says:

        Better still, don’t neuter at all unless your dog is displaying properly diagnosed symptoms which neutering has a better than 60% chance of resolving, and you have investigated all other medical and behavioural treatments first. Good luck!

      • Debbe says:

        We just had to put down a 12 year old golden because of a large tumor pushing on her lungs. I want to know we have been told to spay a female before 6 months so she doesn’t get breast cancer. We had a golden that did just that.So we get them fixed at 5 months. Is this wrong ? Should we wait longer? We have a white golden that is 7 yrs old now. She is our 7th golden. They just can’t be beat.We love them as our own children.And are treated as such.

        • Angry Vet says:

          Goldens are prone to cancer for sure…many types of cancer. While spaying will eliminate (virtually) the risk of mammary cancer it will increase your risk of hemangiosarcoma and osteosarcoma. Both of these deadly cncers are prevalent in the breed as well. If it were my golden, I would let her go through at least one heat and then spay to at least wait for maturity to spay

          • Bridget Duggan says:

            There has been one systematic review of 4 major studies which concluded/supported that mammary cancer risk is higher in intact or “late” spayed females.
            I’d like to hear your thoughts on the possibility that spaying does not offer any protection against malignant mammary tumors in dogs.

          • Angry Vet says:

            it is absolutely true that early spaying reduces chances of mammary cancer to almost nil. Waiting one heat cycle increases chances by about 8 %

      • Michael Sulman says:

        I plan to have my 9 mo. old labradoodle pup undergo an ovarian-sparing spay. Is there an optimum age for this procedure? My vet advises doing this prior to the first heat cycle, as the uterus is smaller & less vascular. She also will perform this laparoscopically.

  4. amy says:

    maybe i’m not understanding correctly, but i see in almost every case except 3 neutering or spaying late as opposed to staying intact lessened the occurrence of issue.

    in addition this overview of records does not account in any way for genetic predisposition.

    interesting, but as many breeds mature more slowly than GR’s and the fact that genetic relationships were not addressed… I’ll be filing this as ‘interesting’ and hope that it leads to a more in-depth assessment.

    tks AngryVet

  5. Bonnie Brown says:

    I was forunate to have studied with a dog trainer in 2003 who taught all his dog training students to wait to spay/neuter at least until a dog is “social normal” as he put it. I am so happy that this issue is now being brought to the forefront. Thank you for that.

  6. Ellen says:

    I feel a bit on the fence about one of the study’s results stating there was an increase in mast cell tumors. From reading about them and comparing certain patterns of cases by people telling their stories on MST blogs, I associate those with an overstimulated immune system most likely caused by vaccinosis, as well as related to very poor quality processed food being a consistent diet (like Pedigree), or maybe a combination of both. I would like to know that information about all of the dogs in the study – their vaccine schedule and protocol. Diet info would be interesting as well to see nutrition values.

    The other diseases/injuries found I can clearly see being related to an premature cessation of hormone production. I will read the study and see if there is any additional information. Thanks for posting.

  7. Karen Kennedy says:

    I got my first dog three and a half years ago and I was going to take the advise of my vet to spay her at six months old. Luckily, a breeder emailed me and begged me not to spay her to at least after one year old.
    Well, I started doing research on the Internet and dug deeper then the current trend … let’s just say I chose NOT to spay her at all! She is going on four now and she does not have a lot of heats, but when she does I put a diaper on her and keep her in … she mainly sleeps. Of course, I am at home all day and there are no other dogs.

    • spencer shears says:

      Best to you and your dog. My question is who in their right mind, in the 21st century, would let a dog, male or female, roam outside and face pregnancy, disease, poisoning, accidents and other malfeasances? And all the talk about pyometria etc. what in heaven’s name do wild dogs do? Do they all die miserable deaths from this ‘disease’? I’m still thinking about all of this, glad everyone else is, too. (PS, female pugs seem to clean themselves…IMHExperience).

    • Michael Sulman says:

      Good for you , Karen! I have a 5 mo. old puppy and plan to let her go through one or two heat periods before I consider spaying. I’m thinking that an ovary-sparing spay is the best way to go. The Parsemus Foundation has some convincing articles + an informative video about the procedure.

  8. Cheryl says:

    I am especially pleased that the breeder of my 10 month old puppy Axel ,advised to not neuter till after 1 year,after seeing this study.This is the 6th dog of the same breed that I have owned.All but 1 of the previous 5 were neutered or spayed before puberty.All but 1 died of canbreedecer ,all but one died before the age of 10.The 1 that was not neutered lived to the age of 14 and was very healthy till the end,he did die of cancer but he lived past the life expectancy of his breed.My last one died at age 4 of lymphomic sarcoma,and had several operations for displacia and cruciate problems.their cancers were swift and horrible,especially the last one.Your article and the info from my breeder and life experience have convinced me that I will be giving a lot more thought to neutering my 10 month old.

  9. I worked at a shelter off/on for nearly 12 years – there was absolutely NO attempt to “educate” clients (I refuse to call owners pet parents or say that pets have been adopted) in the proper care and precautions of having an intact pet. We once got a BEAUTIFUL set of 3 purebred Boxer females (8 weeks old – current on vaccinactions, paper trained, socialized) and before the ink was dry on the intake sheets they were shuffled off to be spayed! I argued to blue in the face – but to no avail. Shelter/rescue mentality is that owners can not be trusted to prevent pregnancy – thus to stop overpopulation – everything on the planet needs spayed/neutered! We “breeders” (oh oh there’s a horrible word!), we breeders have known for years that early spay/neuter is detrimental to the overall well being of the dog. HSUS and others have done a fantastic job of selling the overpopulation myth and promoting the righteous cause of early spay/neuter – – afterall that little procedure cures any/all behavioral problems not to mention rendering the pet incapable of reproducting. I shake my head, I still have dialog with the shelter workers and have yet to make a dent in the ignorant thinking. Thank you for proving what we’ve known for a long time. I wonder how many “adoptions” would go through if shelter workers were HONEST about the probabilities of SERIOUS health issues with those animals who have been spayed before sexual maturity? I’m guessing very few. I know I’m not in favor of borrowing expensive and heartbreaking trouble. Thanks for getting this message to a mass audience – I pray someone will listen!

    • Lesley says:

      ALL of the shelters here will not even allow you to adopt a dog IF you have ANY intact pets at home. Absolutely crazy! I have rescues, and hopefully always will but I also have intact mastiffs so I cannot adopt a dog in Alberta.

  10. Nele Howold says:

    Thanks a lot for your artikle. Here in Europe we have a lot people (including vets) who are against neutering because of the risks of certain diseases. Only animal rescue still neuters every animal that enters a shelter. Hey we live civilisation. One should be able to take care of a bitch two weeks a year……..

  11. Maria says:

    Unfortunately I wasn’t aware of this information when the vey was pressing to get my dogs neutered and spayed. The only think I can do at this point is give others the chance to do it differently and wait to have their dogs neutered/spayed.
    Thanks I will share on my business page.

  12. Ellen says:

    All of the female dogs in my previous life living on LI were not spayed until they developed pyometra. One was 10 or 12 years old, a Heinz 57. One was a Belgian Shepherd and about five or six years old. I lost one whose “surgery was a success but the patient died” later that day due to throwing a clot and having a stroke – she was only 6 1/2 years old. She was a bigger dog, a mix of Newfoundland and German Shepherd with congenital hip dysplasia. Nobody wanted to tell a 19-year-old about a surgery to correct that back in 1979…

    So, is it better to wait until a dog is in an emergency situation and ill to do surgery on them? My current mixed breed pup is 15 months old and just completed her second heat, this one being a more mature estrous. My neutered male dog was very interested this time around and mounted her endlessly. I think she’s past puberty, fully developed, and ready to be spayed before pyometra shows up, which seems to be inevitable in my experiences. I have no intention of breeding her.

    Where does the Angry Vet stand on this issue? Do you see pyometra often in unbred, unspayed females? How would you look for this in a yearly or bi-yearly exam, or do you just have to wait for it to show up? Thanks for posting and responding.

  13. KP says:

    Great article. I think it’s unfortunate that rescues & shelters will ignore this and continue to beat the overpopulation dead horse. Not to mention extremist groups like PETA & HSUS, who do not want ANY pets, will continue to pour money into the spay/neuter machine. The thing is, folks who breed recklessly and without thought and consideration will continue to do so regardless. This leaves the responsible folks that want to obtain a dog from a shelter lumped in with the bad folks and they may be getting dogs with shortened life spans because they have no choice but to get a neutered/spayed dog. Great article and I’m glad I haven’t neutered either of my boys.

  14. Erin says:

    The mounting research that indicates issues far beyond spay incontinence and longer growth periods is one reason why I scheduled a phone consult with a reproductive vet about my options when it comes to spaying my youngest dog.

    We no longer are restricted to two options: s/n or not! I’m currently looking into the pros/cons to ovariectomy (removal of just the ovaries) and hysterectomy (ovary sparing spay) vs traditional spaying (ovariohysterectomy). If I ever have a male dog, I’ll probably keep him intact, but if that’s not an option, I’d want to have him given vasectomy instead of a traditional neuter.

    The more people start looking into alternatives, the more will become available!

    • Angry Vet says:

      ovariectomy IMO is the worst possible option,. You lose the hormones but maintain the uterus and have a chance for pyometra (even though reduced because of no hormones still possible). Hysterectomy (leaving in the ovaries) is something I haven’t done and you do have a chance for a stump pyo but is a possibility. It is not really written up as best as I can tell so far but in theory offers promise

  15. spencer shears says:

    One phrase sticks out ‘…closure of bony growth plates’ (as related, I assume, to HD in GR.) Question !, what other breeds were use as comparison populations? GR are prone to HD. I’ d like to see cross-gene pool evaluation. 2. I know, from practice, that uncut horses do not IN GENERAL, achieve the height of geldings within the same breed, (broad statement, and purely first hand experiential), but an uncut horse’s hormones seem to encourage muscular development, greater (height and weight held as a constant) than geldings. I’d like your thoughts. I loved my stallions but I always have cut my dogs because I can’t stand territory marking. On the other hand, I’ve always left female dogs whole, in spite of the mastitis/cancer warnings. How hard is it to keep a bitch indoors? And no dog should be free-ranging in the 21st century, anyway. And you’re right, Europeans think the whole thing is just more American madness.

  16. Laura Bernier says:

    In your opinion, what is the optimum age to spay a female or neuter a male?

  17. Sheila says:

    I have loved 5 golden retrievers and currently have a 17 month old female. I’ve been truly conflicted about what to do regarding the spay issue with my girl. My first two were not spayed (no counsel from vet) and one nearly died of a closed pyometra and the other to horrific mammary cancer. When #3 golden came along, I had her spayed at 6 months. She had hip dysplasia and cardiac hemangiosarcoma. I read the recent article by Dr. Hart of UCD; if I read it correctly, my intact dog is “protected” from mast cell tumors and hemangiosarcoma … but now is increasingly at risk for pyometra and mammary cancer. Which is the lesser evil? I truly do not know what to do about this. Angry vet…what is your counsel?

    • Angry Vet says:


      Unfortunately there is no easy choice when it comes to female dogs. Spaying before the first or second heat cycle will just about guarantee that your dog doesn’t develop mammary cancer, but may increase the risk of other cancers and developmental orthopedic conditions. You don’t need to perform an early spay to prevent pyometra, as this is less common in younger dogs. One approach that some take is to spay their dogs at a few years of age. The thinking being that at the very least there should be little to no effect on bone growth and this will prevent pyometra. Now, while theoretically the protective effects of spaying dogs at this age relative to mammary cancer would be non-existent, my personal experience has been that it is still rare in this group of dogs. When I’ve seen mammary cancer it has generally been in intact females.

      I spayed my dog at 4 years of age, if that helps. With my male dogs, I never neutered them.

      Dr. Mike

      • Sheila says:

        Thank you for your advice regarding mammary cancer and pyometra. Do you think that spaying – at any age – increases the risk of hemangiosarcoma in a female golden? Are you of the opinion that hemangiosarcoma is inevitable…this is my most grave concern. Thank you

        • Angry Vet says:


          I cannot say for certain if there is an increased risk of HSA in spayed vs intact females. There isn’t enough information yet. However, while we do see some HSA, we do not see it all that often in general practice. Most of the females we see are spayed, so I would say the risk is still somewhat low. There is definitely some breed predilection for certain cancers, with some types of cancer occurring more frequently in some breeds. This will likely play just as large a role as being spayed. I love Goldens, and I myself have a pure breed dog, but pure breeding is going against natural selection, so while hopefully we get the characteristics we like in a pure breed, it is inevitable that unwanted traits are also passed along, such as propensity to develop certain diseases.

          • Monica says:

            I raise Dobermanns and Pugs and have always recommended that females be allowed to have at least 1 to 2 heat cycles before being spayed. Males can be left intact, but all are not to be bred. I thought I would add my two cents about HSA.

            In 21 years I have only had one case of HSA, and this was in a retired breeding bitch. She was spayed at 5 1/2 yrs and had mammary carcinoma, resulting in a complete mastectomy and no reoccurrence. I don’t remember how long after surgery is was exactly, but shortly after my girl would reach under her groin as if something was pinching her. I thought it could have been an undissolved suture, but it continued on.. until she was diagnosed with HSA (Hemangiosarcoma of the spleen), and I lost her at 9 years of age.

            I typically spay my females around that age, that was the only case of HSA that I have encountered over the years.

  18. Lisa Hayes says:

    I have a female Cairn Terrier and a male Scottish Terrier, both 13. At the time I got them, I was advised to have them fixed at six months because it was good for their health. I did so and my female seems fine. However, my male has issues going up and down steps and his hind legs don’t move as well as his front ones. Can I attribute this to the neutering?

  19. Leah says:

    Hi there!
    What is your advice on curtailing a male dobe from marking? He is a great dog, not one bit of anger in him and he lives with a 4 year old chi-mix and 5 kids! But it is the marking that is driving me crazy!!! Any help with this (aside from enzyme remover spray?)?

    • Angry Vet says:


      Most likely this is a training issue not a medical problem. I have always crate trained my dogs. Even for adult dogs it can help. If you aren’t familiar with crate training there are many articles on the web or you can find an article on puppy training on our website eastmeadowvetclinic.com

  20. Bridget Duggan says:

    I meant to include the link to the published study:

  21. Angry Vet,

    Thought you might be interested to see our foundation’s page on ovary-sparing spay, which also gathers some of the health data pro and con about spay/neuter and cancer and is compiling a list of veterinarians open to offering ovary-sparing spay:


    “A way to have one’s cake and eat it too: a way to spay female dogs (thus addressing population concerns), without the increased cancer risk and health impacts from hormone loss (particularly in large and giant breeds) that are only recently beginning to be understood.”

    It also includes a video of expert vet Dr. Michelle Kutzler of Oregon State University demonstrating the procedure.

    • Angry Vet says:


      After some thought on this procedure, we are not in favor of it. There will still be the increased risk of mammary cancer over those dogs that have had the ovaries taken out when spayed. The primary benefits would be population control and pyometra, which we feel would be more properly addressed with the use of a leash when walking and the use of a fence for the yard, rather than surgery. In our opinion, if the goal is to prevent pyometra, the standard OVH is the best choice. We feel that performing this procedure after fully grown may be the best choice for prevention of pyometra, as it will also allow for normal bone growth. As more information becomes available, our opinions may also change.

  22. Angela says:


  23. Angela says:

    My ex-husband is a Chiropractor so when I took in a Cane Corso I read everything I could about Giant breeds. I elected to not have her spayed until 3 months after her first cycle. She is now 12months and has still not had her cycle which is common in a big girl. She is under my supervision at all times so please don’t anyone chime in on spay and neuter..Im doing whats best for her bone development and how it will affect her in her later years. My questions is….Is there such a thing as non surgical spay or something easier to spay her after the event has happened? Thank you and I LOVE YOUR WEBSITE….

  24. Karen Malone says:

    I adopted an adult female Golden 4 years ago and while my vet continues to suggest that I spay her (she is now 10), I don’t want to do it. I intended to when I got her, but due to many financial setbacks over the last 4 years, I just haven’t done it and I feel that now she’s too old anyway. Although the heat cycles can be “messy”, but I don’t have a problem cleaning up after her, and she is never outside unless on the leash, with me. I honestly think at this point there is a greater risk to her if I do spay her. What is your opinion?


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