Dr. James Serpell & Dr. Chris Zink talk C-BARQ & early spay/neuter

Watch our Good Breeder Webinar we recorded with Dr. Serpell and Dr. Zink to learn all about C-BARQ and early spay/neuter.

by Dr. Judi Stella, PhD - Head of Standards & Research at Good Dog

Watch our webinar with Dr. James Serpell & Dr. Chris Zink!

Listen to world-renowned leading canine behaviorist and co-creator of C-BARQ, Dr. James Serpell, and veterinary specialist, Vet of the Year, Dr. Chris Zink, DVM, for a discussion on how breeders can use C-BARQ to breed for behavior and recent research on the effects of early spay/neuter. See a transcription of the webinar below.

Dr. James Serpell's, BSc, PhD:

Director at PennVet’s Center for the Interaction of Animals and Society, co-creator of C-BARQ (vetapps.vet.upenn.edu/cbarq/), author of The Domestic Dog, founder of the International Society for Anthrozoology, committed to the scientific study of human-animal interactions, Professor of Animal Ethics & Welfare at UPenn, and has published many studies and articles on canine behavior, health, and welfare.


Vet of the Year, award-winning author, has put over 125 titles, Co-Founder of Avidog-Zink Ventures, and expert in canine sports medicine and rehab (instrumental in establishing this as the newest specialty in veterinary medicine).

Good Dog Team Panelists:

  • Cat Matloub, Esq.
  • Judi Stella, PhD
  • Monica DeBosscher, Esq.


Zink, et al. 2014. Evaluation of the risk and age of onset of cancer and behavior disorders in gonadectomized Vizslas. Journal of the American Veterinary Medical Association Vol. 244, No. 3, Pages 309-319 https://doi.org/10.2460/javma.244.3.309

Farhoody, et al. 2018. Aggression toward familiar people, strangers and conspecifics in gonadectomized and intact dogs Front. Vet. Sci., 26 https://doi.org/10.3389/fvets.2018.00018

Starling, et al. 2019. Behavioral risk in female dogs with minimal lifetime exposure to gonadal hormones. PLoS ONE 14(12): e0223709. https://doi.org/10.1371/journal.pone.0223709

McGreevy, et al. 2018. Behavioural risks in male dogs with minimal lifetime exposure to gonadal hormones may complicate population-control benefits of desexing. PLoS ONE 13(5): e0196284. https://doi.org/10.1371/journal.pone.0196284

Asher, et al. 2020.Teenage dogs? Evidence for adolescent-phase conflict behaviour and an association between attachment to humans and pubertal timing in the domestic dog. Biol. Lett. 16: 20200097. http://dx.doi.org/10.1098/rsbl.2020.0097


Cat Matloub [00:00] Thank you all so, so much for joining us, and for making these webinars the highlight of all of our quarantines. It’s just so fantastic to be able to connect with you all even more. It’s kind of the silver lining of what’s been going on, so we’re super grateful to all of you for giving us your time. We know how busy you are as dog breeders, but we’re really, really appreciative.

For those of you who may not be familiar with Good Dog and are maybe joining for the first time, we are a relatively new company. We’re on a mission to build a better world for our dogs and the people who love them by educating the public and advocating for dog breeders. What we want to do is help the public realize that the way to have a better dog world—the way to have healthier dogs, the way to have no dogs being abandoned and going into shelters and rescues—that path forward is really founded upon dog breeders and the need to support dog breeders. So, that’s what we’re all about here at Good Dog. We offer a host of support and benefits to breeders who join our community. We’re free for dog breeders. But you also can pay to be listed or featured. You just have to pass our screening. And we are incredibly science-focused and evidence-based. Our goal really is to bring together the good forces in the dog world—empower them with our skills, which are technology, among others—and then really, really just look to bringing together the best experts in all of the relevant fields.

That really underscores how we could not be more excited for today’s webinar, which I think is such an awesome example of two of the absolute leaders and legends in the dog world in different areas. Dr. James Serpell, who just joined us. (It’s great to see you, Dr. Serpell!)

Dr. James Serpell [02:17] Hi!

Cat Matloub [2:18] Dr. Serpell obviously needs absolutely no introduction. He literally wrote the book on understanding dog behavior and human interactions, The Domestic Dog, which is still used as the foundation for behavior with canines and our interactions with them. He also, incredibly, co-created the first canine behavior evaluation tool that can be utilized for breeders, C-BARQ. And that is an awesome, awesome tool that can be used in your breeding programs. He also founded the International Society for Anthrozoology, which is committed to the scientific study of human–animal interactions. He’s currently a professor at the University of Pennsylvania and the director of the Center for the Interaction of Animals and Society. Honestly, his resume is too long for me to go into here, but it’s absolutely such an honor and a privilege to have you here, Dr. Serpell. Truly, one of the founding fathers in canine behavior and our interactions with dogs, and it’s just really amazing. Thank you so, so much for joining us.

And then we’re also incredibly lucky to have Dr. Zink, who has too many degrees and articles and all of that for me to mention here. Female Veterinarian of the Year. Really, one of the world’s top canine sports medicine and rehab veterinarians and researchers, and somehow also, in her spare time, has a full-time job. She’s worked as a virologist and Johns Hopkins for over 30 years on the HIV/AIDS epidemic. Just absolutely incredible. Locks of accolades from the Dog Writers Association of America. We truly, truly could not be more privileged to have you both with us today to talk about such important topics.

We’ll go ahead and dive into things. We’d love to kick things off with Dr. Serpell talking a little bit about C-BARQ and how dog breeders can use that as a tool, and then dive into the really important and ever-evolving topic of spay/neuter. It’s obviously been a controversial subject. People have all different sorts of opinions on it, and they’re just ongoing, as the experts will tell you. But it’s such a critical part of a breeding program and decisions that breeders make, so it’s important to know about the current studies and the current information and what we’re seeing out there.

Thank you, thank you, thank you. And with that, I will turn it over to Dr. Judi Stella, who is our Head of Screening and Standards, who will be leading a Q&A interview with them. Turning it over to hear about C-BARQ!

Dr. Judi Stella [05:29] Dr. Serpell, Dr. Zink, that’s so much for being here. I am excited for this discussion. It’s a topic I’m really interested in. And I do think it’s an important one. So, like Cat said, before we get started talking about spay/neuter, we’d like to ask you, Dr. Serpell, to talk a little bit about C-BARQ, the tool that you developed, and how it’s being used in canine research. And then also, how breeders could utilize it in their breeding programs?

Dr. James Serpell [05:57] Certainly, yeah. The C-BARQ is a survey instrument. It’s a questionnaire, essentially, that was developed to enable dog owners and dog handlers to perform very standardized evaluations of their dogs’ behavior. It was originally developed using, as a model, the kinds of questionnaires that psychologists have developed to get, for example, parents to evaluate their children. That was the model that I used to develop it. My thinking was: these animals are living in people’s homes, often in the same kind of general role as children, so it made sense to ask the owners if they could actually do an accurate evaluation of their animals’ behavior. Anyway, that was many years ago. The first description of the C-BARQ was published in 2003, and we then made it available online to pet owners and various dog organizations. That’s been the case since 2005, and it’s just gradually accumulating behavioral records on dogs.

We now have records on over 50,000 pet dogs and about 40,000 working dogs in this data base, which is a fairly remarkable source of knowledge and information about dogs. It enables us to be fairly precise in the sort of claims we can make about dogs and their behavior. As a research tool, it’s very widely used. I think there are now over 100 published studies that have used the C-BARQ for one study or another. They cover the full range of studies that you can imagine, including evaluating the dog survivors of the Fukushima Earthquake in Japan to much more mundane studies looking at the influence of diet on behavior or the influence of castration or neutering on behavior. A huge range of different types of studies that have made use of this instrument, which is very gratifying. In addition, it’s used by a lot of dog organizations (guide dog organizations, service dog organizations) to evaluate their puppies at particular ages prior to training. This information, it turns out, is quite useful for predicting how likely it is that some of these dogs will be successful in training and go on to become actual working assistance dogs. We have also got a number of breeders using it now to evaluate the puppies after they’re sold. So, the breeder is sending a request out to the owners of their puppies to complete this evaluation, sometimes a year or two after the puppy has been sold. And it’s a way for the breeders to get feedback about how their puppies are doing behaviorally, which may inform their breeding decisions in the future, but also gives them an opportunity to help those owners to deal with specific behavioral issues that might be developing in those puppies later on.

It’s finding a very wide range of uses now, which to be honest, I didn’t anticipate when I developed it. I was developing it primarily to try and understand what the range of behavior was out there in the dog population. The only way to do that on a mass scale was to develop something like a questionnaire.

Dr. Judi Stella [09:49] That’s really interesting. Thank you for giving us a little background on that, and we will come back to C-BARQ a little bit later in the discussion when we talk about some of the research, looking at behavior.

So, now let’s dive into the spay/neuter discussion. It’s interesting because in the early/mid-’80s, when shelters and veterinarians were starting to take seriously the unwanted pet population and the associated high euthanasia rates, one of the practices that they encouraged pet owners and in the shelters was this early spay/neuter. It just became a really accepted practice, part of responsible pet ownership. Everyone got their dogs spayed and neutered. But recently, there’s been some research that’s starting to question those practices and whether or not that’s actually in the best interest, from a health perspective as well as a behavioral perspective. So, that’s what we’re really going to talk about today. I want to start with Dr. Zink. Let’s talk a little bit about some of the research looking at health associations and gonadectomy. I wanted to start with one of your areas of expertise, which is orthopedic conditions. Can you just tell us a little bit about what we know about orthopedic conditions and spay/neuter?

Dr. Chris Zink [11:08] I want to give a little bit of background to this, because I know when I want to vet school, many decades ago, it was already in the ‘70s considered a practice to spay and neuter dogs. There were a couple of studies back then done that showed it was safe to spay or neuter dogs at a young age. In particular, it sort of became standard practice to spay and neuter dogs six months of age. That changed over time, when there was a big move towards spaying and neutering dogs at a much younger age, before they ever left the rescue organization, since many of those rescue organizations were sending out puppies, then there started to be a move towards earlier spaying and neutering. That’s sort of the history of it.

One of the things, in science, that we have to be very careful about is a cognitive error that we very commonly make, and that is that if we make a decision that we believe is scientifically sound, and we decide this is the way to do something—we kind of stop investigating it. And so in the ‘60s and ‘70s and ‘80s, it was decided that spaying and neutering is the standard for pet dogs. And then people stopped investigating it, really. It was only in the last couple of decades where people have started to look at it more carefully and realize a few things.

Back in 1985, I got a golden retriever puppy. I was having a seriously difficult time deciding between two puppies. They both looked the same, they both acted the same. I wanted to make a really good decision. One of them ate poop, and so I chose the other one. It turns out that my dog ate poop, too, so that wasn’t very predictive—but in any case, that’s the one that I chose. When I met the other litter mate at the age of 2, my golden retriever (who was intact, just because my family had never neutered anything) looked like a golden retriever, and his looked like a tall, skinny, weirdly hairy thing that just didn’t look very much like a golden retriever. I was stunned at first. I thought, Oh good! I picked the right one. But what it really was, as I started to realize over the next few years, was that his dog had been neutered at 6 months of age.

I started to look at the orthopedic effects of spaying and neutering. We know that the gonadal hormones, whether that’s estrogen or testosterone, help to close the growth plates, which are the areas of the bone that’s making new bone and allowing the bone to grow longer. The thing about the closure of those growth plates is that it doesn’t happen all at once. It happens in a sequential basis, with some bones closing as early as 3 or 4 months, and others as late as 14 or 16 months, depending on a lot of factors. But it turns out that if you remove those gonadal hormones from the dog, those growth plates close later. And that’s been shown scientifically. So what you end up with is a dog that doesn’t have the coordinated, synchronous closure of the growth plates that makes them look genetically like whatever breed they were going to be; rather, it delays the closure of some growth plates for a longer period of time. As the science started to evolve, we started to see studies coming out showing that there were more problems with cranial cruciate ligament injury, hip dysplasia, some other issues like patellar luxation, that were really orthopedic issues that were much more common in dogs that were spayed or neutered, and particularly spayed or neutered young.

In particular, I’d like to highlight cranial cruciate ligament injury, which is something that a lot of us are aware of and that we know is quite common in dogs. It’s a knee problem at the stifle, and it’s very expensive to get the surgery to try to stabilize that joint, usually in the range of $4,000 each knee. There are actually now 8 studies showing that this problem is more common in dogs that are spayed or neutered. It’s very interesting to me that one of the last growth plates to close in the dog is at the site where that cranial cruciate ligament inserts on the bone. What we’re really doing is we’re changing the conformation of the stifle, so that’s probably one of the reasons that we see that. There’ve been a number of publications in the last, say, 10 to 15 years showing increased incidents in orthopedic problems in many of the larger breeds. So there’s been a study in German Shepherds, one in Labs, one in Golden Retrievers, one in Vizslas. It looks like, at least in the large breed dogs, spaying and neutering prior to puberty increases the incidents of orthopedic problems. These are pretty significant in a lot of dogs, so that’s very important.

Do you want me to go into the study of Vizslas that I looked that myself?

Dr. Judi Stella [17:11] Yeah, if you want to do that now. We were going to touch on it, so if you think it fits in now. I was going to ask you about cancer.

Dr. Chris Zink [17:19] And that was about cancer, so I’ll talk about my own study myself. The Vizsla Club of America (and many clubs have done similar things) set up a retrospective study to look at a wide variety of illnesses and diseases that occur in their breeds, so they would know how to direct any funds that they have that they want to direct to research. They’d know what research to support based on the conditions that occur in their own breed. The Vizsla Club of America did it particularly well. They actually hired a professional statistics company to design their questionnaire and to evaluate it. Many breed clubs just do it ad hoc and ask a bunch of questions, but this club did it really well. When they got their results, they actually found that there were increased incidents of cancer and behavior problems, as well as some orthopedic problems, predominantly in Vizslas that had been spayed and neutered. They contacted me because they knew that I had been talking about some of these orthopedic issues. And I said to them, I really wish you had asked in the survey what age the dogs were spayed or neutered. We could know, as veterinarians, what to recommend for when a dog should be spayed or neutered, because at the time, I really believed that all dogs should be spayed or neutered, regardless of any other factors. And they said, “Oh, yeah, we asked that question. We just didn’t analyze it.” So, I directed their statisticians and told them to analyze it based on groups of dogs: whether they were spayed or neutered at or before 6 months of age, between 6 months of age and 12 months of age, after 12 months of age, or remained intact. In their study, they actually had equal numbers of males and females in each of those groups, so that was kind of cool. We looked at that, and in 2014, I published the study.

The results were astounding to me. What they showed was that, actually, regardless of the age at which the dog was spayed or neutered, those that did have their gonads removed had a higher incidence of all cancers, as well as the common cancers in Vizslas, and very serious causes of cancer which include hemangiosarcoma, lymphoma, mass cell tumors, and all cancers in general. That was really astounding. It didn’t seem to matter, then, what age they were neutered at.

Cat Matloub [20:15] Can I ask a question? When you say “increased risk,” can you talk about what that magnitude looks like? What are we talking about here?

Dr. Chris Zink [20:23] I’ll give you an example. So, we’re talking about an odds ratio. I’ll give one of the specific examples that’s actually pretty scary. Let’s look at lymphoma. It’s a fatal cancer. Dogs can go into remission for a while, but they’ll relapse. When you compare, for example, Vizslas that were spayed or neutered after 12 months of age, and you compare that to dogs that were left intact, there was more than a 5x chance—a 500% greater risk—of getting lymphoma in that group of spayed or neutered dogs, as compared to intact dogs. That’s a lot. 500% chance. One of the things that veterinarians have always thought about is a high risk of mammary cancer. The risk of getting mammary cancer is actually 26% higher, not 500% higher like lymphoma. In fact, in that study, there was a small number of dogs that did have mammary cancer. None of them died of it. Mammary cancer is a cancer that, if caught early, is oftentimes curable. But not so much for cancers like mass cell cancer and hemangiosarcoma.

The other thing that was really interesting was looking at males and females. In all of our groups, there was no difference in males and females—except for hemangiosarcoma. In hemangiosarcoma, for bitches that were spayed after 12 months of age, they had a 1,150% times higher risk of getting hemangiosarcoma than a bitch that was left intact. (It was not true for males, actually.) You think about that, and you realize: I would much rather have a dog have mammary cancer that I can identify early and remove surgically than hemangiosarcoma, which is a very disastrous disease, whether it occurs on the heart or the spleen or somewhere else. My findings were supported by subsequent research by the Harts in California, where they looked much more specifically at Labrador Retrievers, Golden Retrievers, and German Shepherds.

I understand that those findings in cancer may not also follow through for smaller breads. In the smaller breeds, they’re not at as high of a risk of cancer in any case, right? We know that cancer is more common in the larger breeds of dogs. But what this really reveals is not the specifics of whether we’re talking about a Vizsla or a Lab or whatever breed of dogs we’re talking about, or even the fact that we know that they have a greater risk of cancer. What I think that this points out is that we need to be always evaluating the evolving science.

I really like the way you said it, Judi. These evolving issues. It’s an evolving field. So we can’t make that cognitive error, where back in the ‘60s and ‘70s we thought we had it solved. Yeah, spay and neuter everything. Rather, we have to start to make individual decisions as veterinarians. Individual decisions for each dog, based on its breed, based on the owner’s knowledge, based on the home environment, and many other factors that bring things together. I think Dr. Serpell is going to mention this as well, when he starts to talk about behavior, because behavior is a very multi-faceted feature, and there are many things that the C-BARQ questionnaire asks about the home environment that can help us make better decisions, too.

Dr. Judi Stella [24:43] Perfect. I want to just touch on one more aspect of health before we get into behavior. One of the other things that is a huge problem in dog population is obesity. In fact, I looked it up last night, and the Association for Pet Obesity Prevention’s latest statistics from 2019 say that 55.8% of dogs are overweight or obese, and there is this link with spay/neuter and obesity as well. Also, all the other negative consequences of being obese: the inflammatory response, diabetes. Can you touch a little bit on that, too?

Dr. Chris Zink [25:25] The science is out there showing that for dogs that have had their gonads removed, their metabolic rate declines quite significantly, like by 30-35%. When the metabolic rate declines, then the dog doesn’t need as many calories to maintain themselves, and so one of the big errors is that people are feeding their dog a certain amount of food and that’s maintaining the dog just fine. When that dog has its gonads removed, it doesn’t need that much food, and so obesity surfaces. There’s probably more to it than that. But that we know for sure. There are probably other factors to becoming obese. For example, we know that there’s this whole food-in/energy-out, calories-in/calories-out kind of formula. But there probably are also individual breed-related factors. For example, in Labrador Retrievers, we know that there are genetic mutations that are associated with obesity. So there’s probably much more to it than calories-in/calories-out.

I’ll mention that for a number of those orthopedic studies, you could say that maybe these dogs that are spayed or neutered are at risk for developing orthopedic problems because they’re obese. But several of them used obesity as a factor. They ruled that factor out in terms of their orthopedic findings. So I think that the orthopedic findings still stand, regardless of whether obesity is another factor as well.

Dr. Judi Stella [27:07] It’s good that you touched on that, because obesity then also predisposes them to orthopedic conditions, regardless of the spay/neuter thing.

Dr. Chris Zink [27:14] Correct.

Dr. Judi Stella [27:15] That was great. I think now I would like to switch to the discussion in behavior. Dr. Serpell, could you give us just a little insight into how the gonadal hormones impact dog behavior?

Dr. James Serpell [27:29] Yes. Like Chris, I want to emphasize that our knowledge in this area is constantly evolving. We need to get away from the idea that somehow gonadal hormones are only about sex. These hormones have very diverse effects throughout the body of the animal, including its brain and its nervous system. They substantially impact development in many, many areas. We need to get away from this idea that we can just eliminate one aspect of behavior by gonadectomizing a male dog or a female dog. It doesn’t work that way.

The other interesting thing about this is it became dogma that all dogs, essentially, should be spayed and neutered. But based on no evidence whatsoever. It was just an assumption: Oh, if we do this, we’ll get rid of all those undesirable behavior associated with reproduction. But nobody really did a decent study to actually find out whether that was the case. Surprisingly, still, nobody has done the definitive study, which would involve randomly assigning dogs to gonadectomy groups and non-gonadectomy groups and actually following their development. That has never been done. It’s extraordinary in many ways, that people have been practicing this for so long without doing the actual science to see what the behavioral outcomes would be, what the health outcomes would be, and so on. But there we are.

So the studies we’ve done are centered around the C-BARQ, looking at behavioral differences between populations of dogs that’ve been neutered or sterilized for a non-behavioral reason. So we took the animals where the owner actually had a behavioral problem and then had the animal sterilized—we took those out. We just looked to the ones who did it for “birth control” reasons, essentially, and populations of intact dogs of similar breeds and so on. The findings from those studies are quite interesting. The results depend very much on the type of study and what they actually looked at. For example, we did some studies with Paul McGreevy in Australia, looking at male and female dogs separately, and looking at what we call Percentage Lifetime Exposure to Gonad Hormones. In other words, the amount of time that elapsed between when the dog was sterilized that and when the owner completed the C-BARQ, so we get all the C-BARQ data and just crunch the numbers. The striking thing was, especially in male dogs, practically all the behaviors we looked at were worse in the neutered males. It was about 25 different behaviors, and they all went in an undesirable direction. The magnitude of the change wasn’t huge. It would range from something like a 5% change to a 12% change in these behavioral parameters. But nevertheless, it was very striking that they all went in the same direction—with the exception of two behaviors. I think one was marking indoors, which is very much linked to testosterone. And, strangely enough, howling. Howling behavior is more pronounced in intact male dogs than it is in the sterilized ones. In females, the effects were not quite so marked, but there was still the same kind of general trend, particularly for fearfulness and aggression. That tended to increase in the female dogs.

This is very potentially alarming, when you consider how widely these procedures are practiced on dogs everywhere.

Dr. Judi Stella [32:05] Yeah, and it’s interesting that you talk about fearfulness and aggression. If we could continue that a little bit, because that’s a huge problem, and we know that anxiety and fear aggression is all negative, that it negatively impacts the human–animal bond, that it can be a public health issue if the dogs are aggressive and biting other dogs and other people. Can you touch on that, how we can incorporate these findings with the spay/neuter and the behavior and the risks for relinquishment, breaking of the human–animal bond?

Dr. James Serpell [32:45] As I said, the increase in risk is fairly small when you’re looking at these large groups of dogs. The thing that worries me slightly is that I strongly suspect from some previous studies I did that these effects are not the same in every breed. So some breeds may be much more affected than others. And that is concerning, because no one’s really done any cross-breed analysis of these effects. At the moment, we don’t have enough information to be able to advise breeders and owners of different breeds whether it’s safe to sterilize their animals. We don’t have information to tell them what’s the best age to do it, if they’re going to do it. There’s this tendency for people to want to do it before adolescence because dogs, like human teenagers, go through an adolescent patch when they often become kind of difficult and a bit unruly. Unfortunately, people think that that dog’s always going to be like that. But if you leave them intact, most dogs grow out of that phase and they settle down, and they become mature adults.

Dr. Chris Zink [34:10] Like humans!

Dr. James Serpell [34:12] Just like humans, yeah.

Dr. Judi Stella [34:15] There’s a paper published on that; I just saw it yesterday.

Dr. James Serpell [34:18] Lucy Asher did a study, again using the C-BARQ, in a population of guide dogs and found very much these effects in adolescent dogs. They went a bit off the rails for a while.

Dr. Judi Stella [34:44] This has been really interesting. Now, because I have both of you here and you are experts on this (and the whole impetus for this and the whole idea for this discussion came because I stumbled upon the paper that you guys co-authored, “Aggression Toward Familiar People, Strangers, and Conspecifics”), can you both touch on aspects of that paper and what you found?

Dr. Chris Zink [34:59] I feel like aggression is probably the most concerning reason for giving up a dog, either to euthanasia or to a shelter. It’s probably a very common reason. It’s also a very dangerous activity of dogs at times. My co-author, Parvene Farhoody, and I decided to just isolate that and just look at that, and ask if that was a factor related specifically to the age at which the dog was gonadectomized. Yes, we joined with Dr. Serpell and used the C-BARQ data to ask that question: Is there any chance in aggression, either more or less, related to age at gonadectomy? And so we had dogs divided into groups where they were gonadectomized at or before 6 months of age, between 7 and 12 months of age, between 13 and 18 months of age, or later than that, or left intact. Essentially, there’s a belief in the population that intact dogs are more aggressive. I think the main findings of this study were that they aren’t more aggressive. In fact, there was no significant change in aggression—one way or the other—for any of the groups, except for more aggression in dogs that were spayed or neutered between 12 and 18 months of age.

I think it’s just a small piece of what Dr. Serpell has done in the whole behavioral concept. What he’s done with many other authors is much greater, but I think we have to get past this idea that everyone seems to have, that intact dogs are more aggressive, particularly male dogs. We have to get past that. I’d like to mention here that I think there are also options that are available, some of which are available in other countries. In Australia, they have a very viable chemical castration methodology. Maybe Dr. Serpell has done some behavioral studies with that as well; I believe he has. But we also have to understand that removing the gonads is not the only way to prevent a dog from procreating. We have to open that up here in particular. I think there needs to be more research done into some of the other ways of preventing a dog from procreating. I think they should be given as options, particularly vasectomy; they should be given as options to clients who want to prevent their dog from breeding. We have a little more trouble with females. We don’t actually have any good studies on vasectomy of males. Although I know it’s a relatively easy surgery that’s accessible by pretty much any veterinarian. But I think the females are a little tougher because we know that retaining their uterus puts them at much greater risk of getting pyometra, which can be a fatal condition. So we like to get rid of the uterus if possible, if we decide to sterilize the dog, but maybe retain those hormones that are preserved by not removing the ovaries. But, never been any studies on this. That’s a big caution. Just as Dr. Serpell said, the fact that we have not done any study looking prospectively at the effects of spayed and neutered dogs on behavior or health—in a prospective manner with a large sample of dogs—is astounding when you figure the millions and millions of dogs that are subjected to this surgery. And the potential effect, not only on their lives but their family members, the lives of everybody that they interact with.

Dr. Judi Stella [39:39] This has been great. I’m going to try to open this up a little bit with some questions from our attendees. You did touch on the vasectomy, which is great because somebody was asking about that. Somebody is wondering if there were any studies that were done on mixed breeds. Dr. Serpell, you might be able to talk to this a little bit: with the C-BARQ data, I know you’ve gotten some information about mixed breeds too, haven’t you? Do you know anything about spay/neuter in those dogs?

Dr. James Serpell [40:12] Yeah, I’m trying to remember now whether the study that Paul McGreevy did included mixed breed dogs. I think it probably did.

Dr. Chris Zink [40:23] I think it did.

Dr. James Serpell [40:27] The problem with mixed breed dogs is it’s such a diverse category. You don’t know what the mix is. The kinds of people who complete the C-BARQ have to say if they don’t know what breed the dog is, but then we don’t have any information other than the body size as to what kind of dog we’re dealing with. It could be a very large mixed breed dog, or a very tiny mixed breed dog. That makes life difficult from the standpoint of trying to compare them in a meaningful way, with the purebreds. But the mixed breeds, as far as I know, are showing the same effects.

Dr. Judi Stella [41:11] This is sort of off-topic, but somebody asked: Is there any parallel research regarding either health impacts or behavioral impacts in cats for gonadectomy? Do either of you know? (That was not something that we would have prepared for.)

Dr. James Serpell [41:32] I’m not aware of any of them.

Dr. Chris Zink [41:36] I’ve read a couple of articles that seem to show that they have the same effects on growth patterns, but I would say reproductively, cats and dogs are very different. I really would caution about applying anything we’re talking about here to cats.

Dr. Judi Stella [41:55] I know they’ve done some research looking at lower urinary tract disease, and I think male cats are more predisposed to urethral obstructions if they’ve been neutered, but don’t hold me to that. I don’t know if they’ve done great studies on that.

Last thoughts: do you have any thoughts or recommendations for owners and breeders that are contemplating spaying and neutering? What do you think? Discussion with their veterinarian? What would you say are the main things that you should consider?

Dr. Chris Zink [42:39] I’m going to head that one first. In human medicine, we now have a thing called personalized medicine. Several people could have breast cancer, and they’re not all treated the same, because different individuals have different components that may make one treatment more sensible than another. We’re taking into account that individual. I think that as veterinarians, we need to practice personalized veterinary medicine on the dogs that we’re dealing with. I feel distressed that many times veterinarians are the least educated on these issues. We need to really work on helping them understand that this is an evolving question, and that they need to practice personalized veterinary medicine on every dog, taking into account many different factors and the science as it exists currently. Their responsibility is to be cognizant of the current science, because this is something that so affects a dog’s entire life and their relationships with their people. I’ll turn that over to you, James.

Dr. James Serpell [43:51] I totally agree. The only thing I’d want to add is by highlighting the example in Scandinavia, where (at least historically) they don’t approve of surgically sterilizing animals unless there’s a medical reason for doing so. Scandinavia manages to live with a population of dogs that are largely intact for their whole lives. They do not have a pet overpopulation problem. They do not have incidents of dog bites and behavior problems that’re off the scale. This is about people. This is not about the dogs. Most owners who are responsible are perfectly well able to handle a reproductively intact dog. It just requires a different way of dealing with that animal. We should think twice before we subject these animals to these procedures. I can totally understand why you might want to spay your bitch, or if you’ve got a totally obnoxious male dog whose incorrigible and is becoming a nuisance, then by all means, castration is an option you can try. But it’s by no means a guarantee that it’s going to fix that behavior problem. The behavior problem can have nothing to do with its gonads. Like Chris says, treat each case as unique. Handle that case as you think the dog and the owner are going to be benefitted. But don’t just jump in there and automatically recommend that the animal be sterilized.

Dr. Chris Zink [42:51] Let’s not forget that many of these issues are trainable. I’ve had unneutered male dogs my whole life, and they might mark in my house once, but they never do again. It’s trainable.

Dr. James Serpell [46:05] Absolutely.

Dr. Judi Stella [46:07] Do either of you know of any resources that the breeders could hand out, with the pros and cons of spay/neuter, to puppy owners? Anything that’s in lay-language?

Dr. Chris Zink [46:22] I have a document on my website that I encourage people to download. It’s a PDF. My website is www.caninesports.com. You’re welcome to go there, under Useful Information, there’s a PDF in which I summarize with all of the references a number of the recent studies on spaying and neutering.

Dr. Judi Stella [46:53] Somebody asked if there’s a minimum age? Like, if a puppy family really wants to spay/neuter, is there a time limit? At worst, wait till they get through puberty and they at least get those hormones for growth? Or do you have any recommendations?

Dr. Chris Zink [47:17] If they really want to remove the gonads, I would recommend that they let the dog go through puberty.

Cat Matloub [42:23] So, what age? Does that age vary by breed?

Dr. Chris Zink [47:27] 14 months. If they wait until 14 months, that dog’s growth plates have pretty well closed and the risk of orthopedic manifestations is probably, for the most part, done. Although, again, we don’t 100% have the research on that.

Cat Matloub [47:45] And has anyone looked into hormone replacement for those dogs?

Dr. Chris Zink [47:50] They have. There are people studying that. There’s no good data on it. No study that has shown, either a dose or the right hormone. I think it’s very, very complex. Women who have had hormone therapy know that it’s an extremely complex question. I don’t expect that to be solved in dogs very soon.

Dr. Judi Stella [48:17] And there may be unintended consequences, like there are with women too, probably?

Dr. Chris Zink [48:18] Exactly.

Dr. Judi Stella [48:25] Are there any other questions, Monica and Cat, that you guys have seen?

Cat Matloub [48:32] We have an interesting question that is wondering about your opinion on how to handle this with respect to the shelter/rescue world, where there is still obviously a lot of pediatric spay/neuter going on and they have different considerations than the dog breeder world. Is there anything based on what you both know that you would think would be a sensible approach, or that’s not as concerning of an approach as pediatric spay/neuter?

Dr. Chris Zink [49:07] My feeling is that at least for males, a vasectomy is a perfectly suitable way to prevent a dog from procreating, if that’s the shelter’s main concern. It can be done at any age. It’s a relatively easy surgery. It’s almost as easy as doing a castration. I recommend that for males. For females, we’re in a bit of a conundrum. The studies just haven’t been done. I know you can do a hysterectomy and leave the ovaries in, in a female, but we just don’t have the data to say what the long-term effects of that will be.

Dr. James Serpell [49:48] I would agree. It is a dilemma for the shelters, and there is an increasing among of evidence that spay/neuter policies early on did contribute to the decline of unwanted animals that were euthanized. Shelters are very set in their ways on this issue. Now that many shelters seem to have gotten the excess population of animals under some control in some parts of the country, maybe it’s time for them to start being a bit more discerning about this recommendation, or this policy, of neutering every animal.

Dr. Judi Stella [50:37] Somebody asked: With all of this research coming out, are the vet schools starting to pay attention? Are they teaching differently?

Dr. James Serpell [50:52] Yes. I would say that veterinary schools are taking notice of these new research findings and modifying their curriculum accordingly. But that takes a lot of time. There’s a lot of inertia in the system. I think students are also reading some of this literature and are querying their professors, saying, “What about this? What do you have to say about this?” I’ve heard both positive and very guarded responses from the lecturers, who I think are reluctant to step out of their comfort zone on these issues.

Dr. Chris Zink [51:43] I think Penn is a leader in this, because one of my best friends graduated from Penn just a few years ago and she was taught that people should be encouraged to wait until maturity to spay or neuter. It’s a good trend. I agree with Dr. Serpell. It’s a very slow process.

Dr. Judi Stella [52:05] My experience at Purdue was that they were starting to discuss it. There’s a group there that’s doing research with Scotties and looking at TCC in early spay/neuter. They’re looking for that association, so I know they were talking about it a little.

There’re a couple of questions about spaying retired dames. Would you recommend that? Those bitches are probably a little bit older, so they’ve at least gone through puberty.

Dr. Chris Zink [52:34] There’s definitely a risk of pyometra that increases as the dog ages. But also, at Purdue, Dr. David Waters has been supported by the National Institute of Aging to look at aged dogs, and he’s shown definitively that bitches live longer the longer that they have their ovaries. We again have this dilemma. I really recommend for the owner of these retired bitches to at least look into having a hysterectomy. Let them maintain their ovaries but get rid of that uterus that is going to make them at a higher risk for pyometra, which is a very serious condition.

Dr. Judi Stella [53:17] Dr. Serpell, I think this one could be for you: Why are some neutered dogs aggressive towards intact dogs? What kind of policy would you implement at dog parks to avoid fights?

Dr. Chris Zink [53:25] I would love to know that, too!

Dr. James Serpell [53:29] It’s a really interesting question, one that I’ve come across quite a lot. It’s not clear to me entirely why they are. I think the most obvious suggestion is they’re quite intimidated. It’s defensive reaction. The dog shows just because it’s confronted, probably by a male dog that looks much more confident and calm than the neutered dog feels in that situation. It’s defensive behavior, I think. They’re going out of their way to be aggressive towards other dogs, but if they’re approached by an intact male dog, they’ll freak out and then become aggressive.

Dr. Judi Stella [54:23] Because they don’t get that hormonal influence when their brains are still developing as well, during adolescence? Do they ever fully mature? Does they remain more puppyish?

Dr. James Serpell [54:52] I wouldn’t have said they remain more puppyish. It’s a very poorly defined notion, but there’s something about a mature, intact dog that is just more mature. They’re less reactive. They seem to deal with the problems of life in a more stable and calm way. What you tend to see with neutered dogs, when they reach adulthood so to speak, they don’t show that change in behavior. They don’t show that transition to becoming a mature, stable adult. They remain more reactive, more uncertain about their environment.

Dr. Judi Stella [55:51] Interesting.

Cat Matloub [55:54] Absolutely fascinating. Thank you both so, so much. I think we’re all going to be re-watching it. Thank you so much, and thank you everybody for joining us. A couple of things to note: we will be circulating links to all of the studies that you all want to read, which is so wonderful. We’ll be circulating a recording of this webinar. A couple of things to note, also, with respect to how Good Dog can help with some of the questions around spay/neuter: one of the things that we can do is help with follow-up to your puppy buyers. If you are trying to follow up and make sure what your plan was is going well, we can take care of some of that. We’re really excited thinking about C-BARQ and what a huge opportunity that there is there, with respect to all the puppy buyers who are coming through Good Dog. To be able to get you that information is a really exciting thing that we’re looking ahead to. Lastly, as some of you who are Good Breeders may have seen, we have been collecting vet, breeder vet recommendations, as well as breeder lawyer recommendations. What we will do as part of our collection of vet recommendations is try to find some of the vets that are more focused on personalized medicine and who are more up to speed on the latest in spay/neuter. We’ll follow up with all of that for all of you. Thank you, thank you so much to all of you. Thank you, Dr. Serpell. Thank you, Dr. Z. This was amazing. I think we all hope to have you back very much soon. It was a fantastic hour. Thank you everybody for joining us! See you next week.

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