Potential Risks of Neutering and Age at Neutering for Golden Retrievers and Labrador Retrievers

A number of interesting and important research studies have been published in the last 5 years on the subject of the risks and benefits of neutering in dogs, and these have provided important information to help guide veterinarians and owners in making decisions about neutering. I published a narrative review of the literature on neutering in 2010, before most of these papers appeared, and I have been following this area of study with interest and evaluating individual papers as they are published. Though each study has its limitations, as is always true in science, and we must be careful not to overgeneralize the results of particular studies or lurch wildly from one set of recommendations to another on the basis of limited evidence, these studies are influencing traditional dogma about neutering. I have made several significant changes in both the information I give to owners and the recommendations I make about neutering based on the emerging evidence.

Another important study has recently been published which adds to the evidence in this area.

Hart BL, Hart LA, Thigpen AP, Willits NH. Long-Term Health Effects of Neutering Dogs: Comparison of Labrador Retrievers with Golden Retrievers. PLoS ONE 2014;9(7): e102241. doi:10.1371/journal.pone.0102241

This study was produced by the same group which published an earlier retrospective study of Golden retrievers, and it is quite similar in its methods and some of its limitations. The authors reviewed medical records from the veterinary hospital at the University of California Davis veterinary college. The study looked for Golden retrievers and Labrador retrievers from 1 to 8 years of age and evaluated the occurrence of 6 diseases relative to neutering status and age at neutering.

The findings are summarized in Table 1 for Labradors and Table 2 for Golden retrievers. For comparison, I have also extracted similar data from the earlier paper by on Golden retrievers by the same group in Table 3. This paper classified age at neutering differently (early being <12 months of age and late being >12 months of age), so the studies are not directly comparable, but it is useful to scan for any possible patterns that might help us make sense of these complex data.

First off, what does the study appear to show? Well, perhaps the most important finding is that there are significant differences in the pattern of possible effects of neutering between males and females, and also between the breeds. This latter point is extremely important. People tend to jump on the findings from a study in a single breed and want to generalize those findings to all dogs and make broad recommendations based on that single study. However, if the possible effects of neutering differ significantly between two breeds as closely related and similar as Golden retrievers and Labrador retrievers, likely these effects will be even more dissimilar in breeds less closely related. A study of Rottweilers or Viszlas, for example, may tell us little or nothing about what to expect in Beagles or Poodles. This is worth keeping in mind before we rush into making sweeping recommendations for all dogs.

The findings in this study suggest some increase in the risk of some diseases with neutering, but the patterns were not very consistent. Neutering before 6 months of age appeared to be associated with higher risk of cruciate ligament disease and elbow dysplasia in male Labradors but not with the risk of hip dysplasia. In females, however, the pattern was the opposite, with neutering at less than 6 months being associated with greater risk of hip dysplasia but not the other two orthopedic diseases. But in Golden retrievers, neutering before 6 months of age was associated with greater risk of cruciate ligament disease in both sexes, but with greater risk of hip dysplasia only in males, not females.

Comparing the current study with the previous study of Golden retrievers also adds to the confusion. In the current study, risk of lymphoma seems to be higher in dogs neutered between 6-11 months than in intact dogs, but not in dogs neutered before 6 months or after 11 months. In the previous study, however, lymphoma risk appeared higher in males neutered before 12 months but not in females neutered at this age. In another example, late neutering in the first paper seemed to increase the risk of hemangiosarcoma in female Goldens but not in males. This was contrary to the hypothesis that earlier neutering might increase the risk of this cancer. However, in the current study, no differences in hemangiosarcoma risk were found for any neutered group of males or females compared to intact dogs.

There are, as always, a number of limitations that we must bear in mind when evaluating this study. As with the previous study, dogs were those seen at a university veterinary hospital. This is a very different population than usually seen at regular general veterinary practices. The veterinary hospital at UC Davis typically sees seen sicker dogs, dogs with more affluent owners, and dogs that live in different areas than those seen by regular practices in the rest of California. So we have to be careful about assuming than any relationships seen between health and neutering in this population will hold for the very different population of primary care practice patients.

Dogs younger than 12 months were excluded from this study. While the disease looked at are less common in dogs less than 1 year of age than in older dogs, they do occur. If dogs who get these diseases under 12 months are different, in terms of neuter status, from the dogs looked at in this study, that might change the apparent relationship. For example, if dogs who are intact are more likely to get one of these diseases earlier than neutered dogs, then excluding younger dogs would make neutering seem like a risk when it might actually be protective.

Similarly, dogs over 9 years of age were excluded as well. These dogs are particularly likely to get some of the cancers looked at in the study, and again if the ones who do differ in neuter status from the ones in this study, the apparent relationships identified in the study might be very different from the real relationships between these diseases and neutering.

A number of potential benefits of neutering, such as preventing mammary tumors and uterine infections in females and possibly being associated with longer overall lifespans, were not included in this study. While these are not directly related to the questions the authors sought to investigate, it is important that we consider overall risks and benefits when deciding when or if to neuter our dogs. If neutering prevents some cancers and increases the risk of others, for example, we need to make a decision about which effect is greater or more important in a particular dog. This study only looks at a small piece of that equation, namely the risks but not the benefits.

Finally, there are many comparisons made in this study, and each one is evaluated statistically. This can create a problem known as the multiple comparisons problems, in which the usual threshold for statistical significance is not appropriate. It is common, in studies which make multiple comparisons between subgroups and don’t correct for this problem to find a smattering of statistically significant results which are really the result of chance. In this study, I am not certain if a correction for multiple comparisons was made. If not, this could explain some of the significant differences found, particularly when the overall pattern is not consistent between studies or does not fit expectations based on biology.

Bottom Line
Overall, this study does suggest that neutering under 6-12 months of age might be associated with an increased risk of some orthopedic diseases in Golden retrivers and Labrador retrievers. In Labs, neutering does not appear to increase cancer risk. In Goldens, there may be some effect on cancer risk, but it differs between males and females. And in females, it may even be the case that earlier neutering is associated with a lower cancer risk than neutering later in life. But there are a number of inconsistencies and limitations which make these findings tentative at best.

The study also appears to show a strong difference in the effects of neutering on disease risk between even very closely related breeds. So it is important to recognize that the effects seen in one breed cannot reliably predict those that might be seen in another.

No single, universal recommendation for neutering or not neutering dogs of any sex, breed, or age is justified by the scientific evidence. There is some suggestion that females may experience significant health benefits, particularly in prevention of pyometra and mammary tumors, though the evidence concerning mammary tumors is weaker than generally believed. For males, there does not seem to be a compelling, consistent health benefit to neutering, and in large breeds there may be some benefit to waiting until after 1 year of age. In any case, as I always stress, it is important to balance potential risks and benefits carefully.

And not all benefits of neutering are related to the health of the individual dog. Millions of unwanted dogs are born and euthanized in the U.S. every year, and while every client I talk to dismisses the possibility that their dog could contribute to that problem if left intact, most of these dogs are the product of breeding by owned pets. So if you choose to keep your dog intact for health reasons, it is important to accept that this creates an additional responsibility to make sure he or she does not contribute to the serious problem of overpopulation and the suffering and euthanasia of unwanted dogs.

With my own clients, I discuss the complexity and inconsistency of the evidence, the general trends that seem to be apparent, and the important of making individualized decisions based on all the relevant factors, including age, breed, sex, intended purpose, and the circumstances of the owner. For the most part, I recommend neutering of females before their first heat, though the evidence is still not ironclad and more work needs to be done to elucidate the details of potential risks and benefits in different breeds and with different neutering ages. For males, I no longer see a compelling reason to neuter unless there is clear evidence of aggression towards other dogs, however I emphasize to owners that they must be aware of the added responsibility to prevent roaming and unwanted breeding.

These recommendations are different from those I gave when I first graduated from veterinary school, and they have changed as a result of changing and improving evidence. Likely they will continue to evolve as more research is done and we have a better understanding of the issue.

Table 1

Table 2

Table 3

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25 Responses to Potential Risks of Neutering and Age at Neutering for Golden Retrievers and Labrador Retrievers

  1. Pingback: Benefits and Risks of Neutering–An Evidence-Based Approach | The SkeptVet

  2. Bartimaeus says:

    Such wide variation between breeds makes me wonder if;
    1; We are seeing noise in the signal, and need replication before we can really trust these kinds of data.

    2; If there really is so much variation between closely related breeds, how practical is it? It certainly looks like data on one breed does not mean much for another, as you pointed out.

    3; With changes in the popularity of certain types/sires/etc in show breeds over time, how useful will this data be in 10 or 20 years? I would still like to see organized veterinary medicine putting more pressure on kennel clubs and breed organizations to discourage the inbreeding etc. that is associated with so many health problems.

  3. Catherine says:

    “For males, I no longer see a compelling reason to neuter unless there is clear evidence of aggression towards other dogs, however I emphasize to owners that they must be aware of the added responsibility to prevent roaming and unwanted breeding.”

    I agree 100 % Skeptvet and I’m glad you have the courage to print that. I wish more people had your courage.

  4. simba says:

    I’m still confused about the benefits of spaying female dogs based on age. Am I right in thinking that the benefit is greatly reduced if they’re spayed over age 2?

  5. Anthro says:

    “…this creates an additional responsibility to make sure he or she does not contribute to the serious problem of overpopulation and the suffering and euthanasia of unwanted dogs.”

    And how many times have I seen “puppies available” as a result of the failure of this responsibility? “He just got away!” is the usual “defense”–said as if it’s ever so “cute”. I just don’t think pointing this out to people is enough. The people I know who don’t neuter seem to have motives other than anything based on science/health; more like imagined or highly questionable “health” issues.

  6. skeptvet says:

    I think you are very likely right on point 1, which is why I mentioned the issue of multiple comparisons and the lack of consistent patterns. I think it may well be that many of these associations are spurious, which is why replication is so important.

    I agree with you other concerns as well, so only time and more study will tell if these data hold up and really mean anything

  7. skeptvet says:

    The issue you are referring to is probably a study which found significant increases in risk of mammary tumors with each heat up until the third, after which spaying was no longer protective. However, multiple studies have looked at this question, some better quality than this one, and they don’t all find the same pattern. Some still show spaying is protective against mammary cancer, but others don’t. So this isn’t as clear a point as I was taught it was. The full details are in the systematic review of mammary cancer and spaying paper, which I have reviewed and linked to in this post as well.

  8. Beccy Higman says:

    Would you comment in general terms as to when you might advise against neutering before the first heat?

    There is nothing to be done about it now, but given my female GSD’s nervousness I have wondered if we would have been better neutering her later. She is a rescue who came to us at about five months having spent the first four and a half months of her life in a shed so missing all of that first critical socialisation period. The rescue we had her from insists on early neutering so this is what we did. We have done a lot of work with her and she has even learnt to bark at strangers now, but I can’t help wondering if this is the type of situation where a later neuter might have been beneficial. We are highly likely to get more rescue GSD’s in the future, although as it is the teens that are tend to be re-homed when people find they can’t cope possibly not one so young. And I’m not looking for a definitive ‘you should have done this’ or ‘next time do that’ so please don’t hold back on that score.

    And I may have missed this looking through the site, but I am interested in the apparent huge variation in the probablitiy of various diseases in different breeds and whether it is real or an artifact of the analyses, which you touch on in this article, so if you can point me to anything solid on that I’d be grateful.

  9. simba says:

    Thank you! That was very helpful, especially considering the ‘a man in the pub told me’ nature of my hazy recollection of the scientific evidence. Congrats for providing a reasoned and informative response.

  10. skeptvet says:

    I don’t think the evidence is strong enough to really indicate risks of neutering before first heat are greater than benefits. One could argue that waiting until ~ 1 year might reduce some risks in a few large breeds (e.g. Golden retrievers, no specific research on GSDs I am aware of), but at this point it’s not entirely clear. FWIW, I always get rescue dogs from shelters, and they have always been neutered very early, and they have all lived unusually long and healthy lives. Whatever changes there are in risk, pro or con, with early neutering are statistically nudges of risk against a complex background of other risk factors, especially genetics.

    I also see the type of behavior frequently, both in dogs missing important early socialization experiences and in herding breeds in particular. I work with a local GSD rescue, and my impression is that nervousness/anxiety are a quite common side effect of breeding for attentiveness, intelligence, and of problems with socialization. So I’d be inclined to think neutering had little or no effect on this issue, though again the research isn’t all that solid.

  11. Beccy Higman says:

    Thanks for taking the time to reply.

  12. Catherine says:

    I have read on various websites that neutered dogs are more likely to die from cancer and auto immune diseases and that intact dogs are more likely to die from trauma and infection. Is this true?

    Trauma, I understand. It’s getting hit by a car or hurt in a dogfight, etc.

    It’s the infection part I don’t understand. Exactly which infections are meant here? I’ve had dogs for years. I’ve had spayed, castrated and intact. They all got the same level of care. They were all protected by being kept confined, never allowed to roam.
    They all received the same veterinary care, vaccinations, and such.

    So, what exactly are the infections that the intact dogs are more likely to have? Could it be infections stemming from trauma? I’ve heard of dogs dying from infections emanating from dog attack bite wounds. Is this what is meant?

    There is so much information, speculation, and misinformation out there. It’s oftentimes hard to get the straight dope, so to speak, and that’s why I love this site. I can always count on you, Skeptvet, to be a straight shooter and tell it like it is, with sound science backing you all the way.

    Thanks.

  13. skeptvet says:

    I’m not sure what claims you have read, so it’s hard to know how to answer them. Intact females are, of course, prone to pyometra (an infection of the uterus) due to hormonal factors, and neutering prevents this. Similarly, intact males can get infections of the prostate gland, which are not seen in neutered dogs. So perhaps those are the infections you have heard mentioned?

  14. Catherine says:

    Ah! That makes sense, Skeptvet. Thank you.

  15. Susan says:

    Do you feel the recent research studies (UCD Golden, Viszla, Lab vs. Golden) provide any additional clarity for neutering of performance dogs?

    Chris Zink reviewed the lit in 2005 (with an extensive revision in 2013) and made recommendations on neutering for canine athletes. (In short, let females have at least two heats before spaying, leave males intact or vasectomize.) The two sports medicine vets that see my agility dogs recommend waiting to spay for as long as is possible. I realize that different subspecialties may view the data differently…different clients/patients, different needs.

    Thank you for your blogs on this topic! It really helps to have someone look at the research and put it into some perspective.

  16. skeptvet says:

    Thanks for the comment.

    I’ve written about the other UCD Golden study and the Viszla study in detail. The Golden study has its limitations, as all studies do, but it does add some useful data, and I think it supports more caution about neutering in large-breed dogs, especially males. The Viszla study is a bit more problematic based on how it was conducted, so I think there is less useful information there.

    Dr. Zink is absolutely correct to question traditional practices on the basis of a careful reading of the available scientific literature. I differ a bit, though, in how I interpret the data. Dr. Zink rightly points out the limitations and risk of bias in studies linking neuter status and mammary cancer, and I agree the evidence there is not as strong as often suggested. However, the studies Dr. Zink relies on to support risks associated with neutering also have similar limitations and risks of bias which he does not address. In general, I agree that there is not a compelling reason to neuter males as long as the owner is willing to take on the added responsibility of preventing unintended reproduction. However, I disagree that the evidence supports better overall health and performance for females if allowed to have two heat cycles rather than being spayed before the first heat. I just don’t think the evidence is good enough to support such a recommendation yet.

    Dr. Zink’s review is, like mine, a narrative review reflecting one individual perspective and set of biases, not a systematic review, and in his case he places more emphasis on the risks and less on the benefits of neutering than I do. The evidence is obviously not clear cut or there wouldn’t be a need for debate and discussion about it. I don’t think his interpretation is unreasonable, but I tend to recommend neutering females earlier, before the second, and perhaps before the first heat depending on breed, owner’s circumstances, and other factors. I think there is still lots of room for different approaches, and the best thing to come out of the recent research is the understanding that rigid, one-size-fits-all rules are seldom justified.

  17. Jennifer Robinson says:

    The topic of when and when not to breed is a little off-topic . . . but one where there seem to be strong opinions and lack of evidence. Hope you don’t mind questions on that line.
    I’m an all-but-retired Labrador breeder who has kept only girls. Somehow the boys I’ve tried to bring along have all failed some test. My feelings about spey/neuter are inclined to be greatly influenced by the qualities of the dog or bitch. In my opinion, if I end out with a bitch who comes from healthy lines (longevity, hips, elbows, cancer, allergies, skin conditions, epilepsy, etc.), who tests well radiographically and genetically, and who has a history of throwing quality (temperament, health and conformation) pups, plus being a good mother, it is ethical to breeding from as long as her fertility holds, and to spey when fertility declines.
    The repro vet I’ve used most contends that regular (ie, every season, or every other season, but not skipping many seasons) was healthy, in reproductive terms, and that it was probably better to spey a bitch once she was out of the breeding program. He claimed there was not evidence against breeding a healthy eight year old who had already had several (5+) litters, or against producing back to back litters (ie., breeding every season).
    The scandal of ‘puppy mills’ and liturgies against ‘back yard breeders’ have greatly colored the picture for breeders who are trying to produce healthy dogs with good temperament, and resulted in a variety of kennel club regulations that contradict the advice I was given by my repro vet.
    Have you seen, or can you recommend any research evidence that treat the question of age and frequency of breeding?

  18. skeptvet says:

    Great question. This isn’t an area I know much about, so I don’t know of any research off the top of my head. If I get a chance, I’ll take a look, but I’d be interested in anything you come across.

  19. Jennifer Robinson says:

    Here is a a link to bibliography relating to the issue put together by one of the founders of the Master Dog Breeder’s Association (in Australia)
    http://www.dolforums.com.au/topic/259148-references-please-early-and-often/

    Another link that draws on the same sources:
    http://americanleopardbreed.proboards.com/thread/1242

    The repro vet who advised me served as a reproductive advisor for Guide Dogs. I would be happy to provide his name, but not in a public forum.

  20. Kelly says:

    So, could you break it down much further for me please?
    We just got a male puppy purebred Golden Retriever from an established, trustworthy breeder. What age, if at all, should we have him neutered? (in your opinion)

  21. skeptvet says:

    Well, of course the fundamental point is simply that there is no one right answer. No matter what you decide, there is no guarantee good things will happen and bad things won’t, so you shouldn’t feel tremendous pressure to make the “right” decision, because there is no single right decision, and lots of options are equally reasonable.

    On balance, from the point of view of individual health, it is not absolutely necessary to neuter male dogs. Overall, neutered and intact male dogs are equally healthy, so either choice is fine. My own preference is not to neuter males if there is no specific reason to do so.

    From a broader perspective, of course, neutering helps prevent unintended breeding, and it may prevent some undesirable behaviors such as aggression or roaming in search of females in heat. If you choose not to neuter, you have to accept the added responsibility of preventing these things.

    If you do decide to neuter, I generally recommend waiting until large breed dogs are fully grown, about 12 months of age. There is weak evidence that earlier neutering, and maybe later neutering also, may increase the risk of some diseases in this breed, though the weakness of the evidence makes any firm rule about age to neuter unreliable. About 1 year is a fair compromise based on what is known now, though it wouldn’t surprise me if future research changes that.

    Good luck!

  22. Ggt says:

    Good article. We own three gsds….two females and one male. We had our females spayed when they were close to a year old because of their breed. One of the females has severe HD, but genetics is probably to blame. The other female and the male have good hips. Our male is intact and he is not aggressive.

  23. Marc Romano says:

    We have a female golden retriever who has just turned one year. Spaying is such a serious and altering act, and we’re on the fence.

    Every single vet we have spoken with, every paper and study we have read, every opinion we have entertained, does nothing more or less than this piece. We are no more clear, no more informed, and no more prepared to make a decision after reading this pice.

    We simply cannot draw any reasonable conclusion based on our extensive reading, the data we’ve seen from multiple studies, the opinions we’ve reviewed – including yours, jean dodd’s, and those of several other veterinarians and researchers, or from the experiences of other golden owners. Nothing has moved us off the fence. Nothing has given us any degree of clarity about this decision. We simply do not feel well enough informed by and through the practice of veterinary medicine to make this decision. I have to hold the practice of veterinary medicine responsible for this complete lack of reliable data that can and should provide the level of clarity needed by dog owners to make an informed and confident decision about an area of practice that is nearly as old as the practice itself. The issue is not with the data, it’s due to a lack of investment in the practice and veterinary medicine and supporting research that can provide conclusive evidence. Instead of burying us in more conflicting data, more conflicting studies, more conflicting opinions, and more complexity, provide the answers to two questions in clear fashion and supported by the fundamental truths in the data.
    1. What should we do?
    2. Why should we do it?

  24. skeptvet says:

    You won’t like this answer, but at some point your real problem is that you are seeking a kind of certainty that almost never exists in medicine. Sure, more data would be better, but there is no chance that any amount of data will ever eliminate uncertainty and give you a single, simple answer. Life is just too complex for that, and we all have to find a way to cope with the inevitability of uncertainty. Part of the reason why pseudoscience and snake oil continue to thrive in medicine despite the obvious success of a scientific approach is that pseudoscience can offer certainty and ignore nuance and ambiguity. But the price for such certainty is ignoring reality or just making stuff up.

    I can certainly give you my interpretation of the evidence, and you are free to follow it or ignore it if you like. However, that doesn’t take away your responsibility for making a decision or for accepting the imperfect predictability of the consequences. I happen to believe the evidence supports spaying any female dog not intended for breeding. For large breeds, such as golden retrievers, I think the best balance between the many conflicting risks and benefits is to do so after full growth is reached, around 12-14 months of age. This appears to reduce the potential negative consequences of removing the gonads (some increase in the risk of some orthopedic conditions and cancers) and also eliminates the risk of uterine infections (pyometra) and minimizes the long-term risk of mammary cancer. This seems to me, based on current evidence, to be the best compromise for large-breed female dogs.

    Of course, spaying before the first heat would probably reduce the risk of mammary cancer even more, but this would come at the price of increasing the risk of cruciate ruptures and possibly some cancers. As I’ve said, the problem here is not simply insufficient data but the reality that every choice increases some risks and decreases others, that every individual responds differently based on genetics and environmental factors, and that ultimately complexity and uncertainty are just inevitable facts about the world we have to learn to live with.

    Good luck!

  25. Marc Romano says:

    @Skepvet. I may have taken an unorthodox path toward being told what I needed to hear, but I believe you’ve just given me the answer needed get us off the fence.
    ( I also worry about her getting through it but I’ve been told it’s quite routine although considered somewhat major surgery.)

    A mentor of mine once gave me a golden piece of advice as it relates to my own clients and my struggle at times with either following misguided direction for the sake of the $ or putting the facts on the table. He said: “They need to hear the truth. You have to put the truth on the table, and if they can’t handle it, walk.”

    He was right. Your response back was right because it was based on the truth. Thanks for getting me off the fence.

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