When Should You Spay /Neuter Your Dog? Science on Joint Risks, Cancer & Ideal Timing (9–12 Months)

Added: 2026-05-31

[00:00:00]When and why to new to your pets? This is a common question, not just for you, for pet parents, but for us vetinarians as well. Tons of new research is going on. And this is a topic that we discuss nearly every single year at National Conference. There's some good points on either side on when to do it. And we're not debating if it should be done at all. We're more debating the time and the most perfect time. And so today we're going to be discussing um the literature, both old and new, and the pros and cons of why to spay and neuter and when may be the most appropriate time. Of course, obviously, conversations with your personal veterinarian are going to be key here because there are lots of nuances that factor into this um as far as the size of the dog, the capability of the veterary practice, increased costs as dogs um get larger. And we are going to be focusing today specifically on dogs, not on cats. Um because we're going to be talking about size and breeds and things like that um that are unique to our canine species. And so let's get some baseline kind of knowledge just to make sure everybody is at the same level. We are talking about ovario hysterctomy or removing the ovaries and the uterus. Some places will remove just the ovaries. Um but surgically sterilizing the female, we are calling that a spay. In the male we are calling it neutering. So that is the removal of the testes in most cases. There are some places that will do vasectomies. That is not very commonly done and there are reasons for that. Um but we are talking about surgically um making the male dog sterile. We are calling that a neuter.

[00:01:39]So we're going to start out with the male. That's the easier species. There's a little bit less nuances there. And what are the reasons why we recommend as veterinarians neutering the male? So with a male, when you neuter them, obviously you're removing the hormones, you're removing the testosterone that is being produced in the testicles. And so when you do that, you are going to be um the idea or the reason behind that is you're obviously removing the ability to procreate. And so we are eliminating that pet population situation. This is why many shelters will do that, spay and neuter programs. and both a male and a female. We have been having these spayneuter programs for a long time.

[00:02:18]Whether or not we are even putting a dent in the pet population, um you know, that remains to be seen.

[00:02:25]However, for your own personal, you know, at home um situation, you may not with the male, not so much, but if you have both the male and the female, you may not want, you know, an unexpected litter. You may may not want to have to deal with 2 3 4 5 6 7. I've seen puppies up to 13, 14. um and larger big dogs, you may not want that responsibility.

[00:02:45]And so, obviously, castration is going to put a stop to that. Um other reasons to castrate males, um we do see decreases in obviously or elimination of the possibility of testicular cancers.

[00:02:57]So, if the testicles aren't there, you cannot get cancer of them. Um we see decrease in conditions like um complications to benign prostatic hyperlasia. So, if you have an intact male, the prostate over time will get large. And even though the the condition is called benign, it can have very non-benign effects on your male dog. And so, as that prostate enlarges, um, they can have difficulties urinating. It presses up on the urethra and you can have poor stream and things like that.

[00:03:26]The other issue is as the prostate enlarges and we do have extra pressure that needs to be emitted for urination um and we get some thinning of the muscles in the buttox area, we can get what's called a paranal hernia and that is where they actually herniate um back in the rear end and those hernas can then trap um the bowel in there. They can trap the bladder in there and it is a very difficult procedure to fix. There are many general practitioners that will not do it. Um, and it can be quite costly to have the repair done at the um, specialty clinic and so a lot of times having them neutered and preventing that benign prostatic hyperplasia will totally eliminate both the difficulty urinating um, pore stream as well as the um, you know, herniation that can occur back there and then you know eliminating the testicular cancer.

[00:04:15]um you will help truncate or prevent some of the unsavory behaviors that you will get with un um castrated dogs. And so the marking, the mounting, the roaming. Um there is no guarantee that you will eliminate aggressive tendencies, but we do know that males of our animal species that are intact do tend to have more aggressive and more impulsive behavior. So, um, yes, I know there are plenty, you know, intact male dogs out there that are the most perfect gentleman's, but we know in general as a species that testosterone does drive, um, some of those more impulsive behaviors. And so, we know that bulls are more aggressive than um, steers. We know that stallions are more aggressive than gelings and so on and so forth. And so even though it is not a guarantee that if you have your pet neutered that they will not show signs of aggression, there is some um belief that we can truncate some of those behaviors if they are neutered. So for the male, those are kind of the health benefits and the why we recommend neutering. And then the second question is, okay, I've decided that I do want to have my pet neutered.

[00:05:22]When is the most appropriate time for an insect male dog, you know, to have that procedure? And here is where there is a little bit of nuance and things that you need to discuss with your vetinarium.

[00:05:35]And so in the male, we are not we're not racing with time to try to get that done at a specific time like in the female where we are racing. We will discuss with the heat cycle. Um so we do have a little bit more laxity there on when it can be done. But the important thing is that it should most vetinarians agree that it should be done. And so if you're one of those people that are going to forget to do it or it's going to be pushed to the background and maybe if we don't get it done, you know, sooner rather than later, it may never get done at all. You have to be honest with yourself, you know, with that um information and you know, your own personal lifestyle. So be honest with yourself. If you know if I don't do it now, I'm never going to do it, that may be a reason um to do it sooner rather than later. Now, we when I say sooner rather than later for this particular series, I'm not talking about um dogs that come from the shelter or dogs that come from a rescue group where they are trying to get those pets spay and neutered before they get adopted at a young age less than 6 months. We are not talking about pediatric spays. We're talking about spays and neuters that are happening at 6 months or older and when is the best time after 6 months. So, we are not talking about pediatric here. um we are talking about dogs that are older than six months and when is the appropriate time and the most optimal time to do it um in within that age group. And so for the male dog, we do have some leeway there. And so for the male dog, based on some current data and literature, we do feel that we want to ensure that the growth plates are closed. Um, growth plates close at about nine months or older depending on the size dog. So, larger breeds tend to be a little bit later. We may see those long bones close um somewhere between 12 and 18 months. Our smaller breed dogs, we're talking about less than 20 kg. We can see them close closer to 9 months. When we're talking about growth plate closure and deciding whether and time to spay and neuter our pets, we are talking about the closure of the long bones. So we have very many bones in our body.

[00:07:37]Pets have very many bones in their body.

[00:07:39]But the ones that we were talking about that um are most concerned about for this particular situation are the long bones. So it doesn't matter to us when a pinky bone closes. It doesn't matter to us when a skull um bones close. We're talking about the long bones. We're talking about the femur. We're talking about the tibia. We're talking about the humorris. We're talking about the radius. We're talking about the ulna.

[00:07:58]Those are the long bones. And so those um radiographically we know when they close. Okay? It's not necessarily a subjective or we're just picking a place and time. We know when those close radiographically there is evidence and we know on average for most dogs that's going to be about 9 months of age. And so if you are considering neutering your pet, ideally um depending on the size, again talk with your vetinarian. We want it to be as close to when those growth plates close or after those growth plates are closed as possible. So 9 months to 18 months. You can always, I guess, get a radioraph snapped if you, you know, absolutely want to know for sure. Um, you can do some measuring measuring. So, we're not going based on weight. We're going based on when the long bones close. So, the height. So, when your dog stops getting taller and they start getting wider, that is um considered to be the ideal time for them to get neutered. Now, there are certain breeds where they are predisposed to having um back problems. So, we're talking about our dachshunds and our Frenchies um where having them um definitely even though those are less than the 20 kilograms that um we originally were talking about, we know that even in those small breeds that having them neutered a little bit later so we get a little bit more muscle mass and we get a little bit more um you know stability there that later neuter on those. So, 18 months um would be kind of appropriate to discuss with your veterinarian in those specific breeds.

[00:09:26]So when you neuter a dog and you remove the tesa the testosterone, what is happening is that testosterone um causes the growth plates to close a little bit faster. Estrogen um that is still circulating in their system, that is what allows those growth plates to close later. So the longer and the longer and the longer the bones get because we don't have that testosterone anymore.

[00:09:49]that is what we are um now theorizing causes some of the osteoarthritis and the developmental issues that can happen later down the road. So when you neuter a dog um they are going to be taller. So steers are taller than bulls. the end weight, you know, is about the same, but it's a different confirmation. And so, we are shooting for that confirmation in these male dogs where we're going to have um a little bit of a shorter stature and maybe a little bit more muscular build versus the taller, more lengthy, more um kind of I guess just taller in general. And um you know, we want to try to truncate that to eliminate some of the orthopedic issues that we are seeing based on some um current literature. and we're going to go over some of the papers and they're going to be linked into the description box below. So, long and the short of it is male dog, you do have some leeway.

[00:10:38]Um, sweet spot's probably going to be somewhere between 9 to 18 months depending on your breed. And so, talk to your vetinarian. The older dog gets, the larger it gets. You may have some incurred cost. So, that may factor in to your um decision- making process. But if you want to know specifically what is the sweet spot, the sweet spot is when those growth plates have closed. Um that is the time to go ahead and do that. And so that is most likely going to be um some of the recommendations that your veterinarian are going to recommend. Now um for the female, so there are different ways the spay can be performed. We're not going to be getting into the specifics and the nuances of that, but you know, ultimately what we are doing is we are trying to stop or remove the ovarian activity. We are trying to stop um and remove the estrogen and the issues that estrogen can cause. So early studies have shown um and we still use these but there is you know some debate on how valid they are. But in general we do seem um to feel as a veterary community that there is some validity there and we do still consider these numbers that if you spay your dog before the first heat they have about a 0% chance of getting mammorary cancer. If you wait till after the second heat you have about an 8% chance um in mammorary cancer. if you wait till after the third heat 25% and then after that you get no protection against breast cancer. Um breast cancer in dogs can be benign or it can be malignant but the bottom line is one out of three dogs that are intact will get breast cancer and that's a significant number. Now, yes, about 5050. 50% are ben benign, 50% are malignant. But I will say this about um benign and malignancy. Number one, there isn't a real easy way to know um without removing the tumor whether or not you have a benign tumor or a malignant one. Fine needle biopsies are not very effective in tissue tumors and so um memory tumors. And so we end up having to completely remove them or take a chunk of them in order to properly know in the first case whether you have a benign mass or a malignant one. Um malignant meaning it's going to metastasize somewhere. It's going to go to the liver, it's going to go to the lungs, it's going to go to another organ. Benign, even though they do not tend to metastasize, they are still locally present and still cause local issues. So they can get quite large and cause mobility issues. um they can still cause pain and discomfort because of swelling in that area, you know, distension of the skin. And so just because a tumor is benign um deemed medically benign, does not mean that it is not causing your pet discomfort. So keep that in mind. Um and so those are kind of the numbers and those are the original numbers that we were looking at when we were starting to recommend um earlier spays in dogs to try to dramatically reduce that because one and three is a pretty significant number.

[00:13:27]last week alone saw three dogs in my small general practice um with mammorary tumors and um none of them one of them had surgery the other two uh the people were not able to do surgery and um you know it's a quite painful process for the pet and you know I don't know what the outcome will will be with those and so very very very common um the other reason and one of the major even um you know there's no question about this is when you spay a dog you eliminate the possib possibility of them getting a pyometra which is a life-threatening emergency where the uterus itself fills with um pus. It becomes a big giant abscess and that big giant abscess obviously leads to septasemia and you know if left untreated will result in death of the patient. That is extremely common. It is more common than the one out of three um mammorary cancers. It happens all the time. And so when a um pet is not spayed and the uterus is still there, as the pet cycles and the cervix opens, bacteria can travel up into the uterus. Um and then when the cycle ends, the uterus closed down and that bacteria gets trapped in the uterine body, forming what essentially is a giant abscess inside the body. A lot of people, you don't see it obviously. And so a lot of people do not know that that is going on until the pet is very very ill um and requires a emergency surgery. Those emergency surgeries um are very taxing on the pet.

[00:14:56]Um they are already decompensated. A lot of them are extremely sick, extremely dehydrated. Um and they are quite costly. So a lot of people find that um these have to be done on an emergency basis and the finances just aren't there to perform the surgery. Um it is a surgical condition. So surgery is the only way to do it. There is not any amount of oral antibiotics um that will fix this condition. And we know that there is a um age-old adage that we all learn in veterary medicine which is never let the sun set on a pyometra.

[00:15:27]That means if we diagnose it and it's 4:30 on a Friday, that dog needs to get surgery immediately. That's how sick these animals are. And so one of the major reasons for spaying a pet is that we completely eliminate the possibility of that happening. And so that's one of the major reasons why we do it for the female um along with the breast cancer and of course not you know not having puppies. And so when is the best time to do that with a female dog? Um some recent literature again male and female suggest that if you have a pet that is 20 kg or 40ish pounds or less it doesn't matter the time that you spay and neuter them. There is no significant um you know differences. And so if you have a pet that is less than 40 pounds, you can just, you know, breathe a sigh of relief. You can do it whenever um is a you know something that you discuss with your family and your vetinarian.

[00:16:20]Time isn't really a factor there except for the mammorary cancer of course you know. So, if they suggest doing it a little bit earlier, you don't have to worry about some of the muscularkeeletal problems that we see um in the older dogs or excuse me, we don't you don't see the muscularkeeletal problems we see in the larger breed dogs or dogs greater than 40 kg.

[00:16:39]Um some of the other So, let's talk about the muscularkeeletal um situation here. So, same rules apply.

[00:16:48]Um we want to have them spayed in that sweet spot that is when the growth plates have closed. um you know they've reached full skeletal maturity but we have the added difficulty of trying to time that where we get the maximal effect of reducing the breast cancer.

[00:17:06]And so um a lot of the larger breed dogs will have heats that are later um and so a normal dog will go into heat starting about 6 to9 months and they will have a heat cycle every 9 months. And so that's kind of a rough estimate. Smaller breed dogs um a little bit different. larger breakouts a little bit different, but that's in general when we're going to see um that occur. And so, how to time that can become um very difficult and this is where conversations with your vetinarian are really important. And so, in my opinion, to try to hit that sweet spot. Obviously, there's a lot of dialogue that has to occur, but for a lot of dogs, doing it about 9 months to a year is going to put you in the time period where um we are close to or right around that first heat, maybe before the first heat, maybe just slightly after that first heat, certainly before the second heat, but we still get the benefits of that muscular skeletal system becoming mature and decreasing the chances of having the skeletal issues later in life. So osteoarthritis, hip dysplasia, cranial cruciate ligament ruptures, that's going to be for the male and the female. Those are the conditions that we are trying to minimize. And so 9 months to a year, maybe a little bit longer cuz if we pass that first heat at 9 months, you know, we kind of have another 9 months. We have up to 18 months to try to get that done. But I would recommend trying to get it as close to before or just recently after that heat um at 9 months.

[00:18:30]And that to me is going to be the sweet spot where we're going to have the orthopedic protection. We're going to have the obviously protection from pyometra and we're going to have one of the most least chances or the better numbers better statistical numbers for decreasing um the mammorary cancer. Now there is some literature hanging out there that talked about urinary incontinence. And so um yes there are papers that show that spade females um have urinary incontinence. The original papers were um saying a you know a certain age pediatric space or space less than a certain amount of time or in at an increased risk of um urinary incontinence. But now we know with more recent papers and more literature that it does not matter the age of your pet when they are spayed in relationship to urinary incontinence. It's just the fact that they are spayed um in general. So whether you have your pet spayed before the first heat, after the first heat, 7 years, 8 years, 9 years, 15 years of age, um it does not matter. Um the incidence of urinary incontinence is still going to be there. It is just a function of removing um I guess we believe that hormone that you will have some urinary incontinence. I do not see urinary continents as often as I see pyometria or um mammorary cancer for so for me the urinary incontinence thing is kind of easily managed with medications and so it's it's not a big factor in my recommendations at this point in my career now if more literature comes out we may change that recommendation other things to consider and these are coming from a practical standpoint um as a veterinarian um not necessarily backed up by literature or anything like that but you know we practice in the real world we don't just practice this based on what is published you know in JAMMA.

[00:20:12]Okay. So real world talking about real world experience here. Um a lot of people will come in they will have their puppy shots done. Everybody knows puppies need a puppy series. They will have the puppy shots done and we will not see them again um for many many many years. And so we already talked about that sweet spot spot is between 9 months to a year maybe 18 months um for our large and giant breed dogs. And so, um, you know, we lose that spay on a lot of those pets from a veterary standpoint if we don't have that done before they fall off the radar after that last puppy series. And so, um, it is where as a veterinarian, we don't like to judge people. We don't like to assume something, but if it seems or the history for past pets shows that maybe we kind of fall off the radar there, we may push to have that pet spade um you know closer to the finish of those vaccines rather than say, "Hey, we know you'll be back in at your appointment.

[00:21:08]We'll talk about it again. If you've not done it yet, um we'll you know, we'll have that conversation." If we have an inkling that that conversation may never happen.

[00:21:19]The other reason um may be limitations at your veterary practice and so not all veterary practices are the same. We have some small ones, we have real ones, we have large ones and they may just may not be equipped to perform a spay on 150 lb mature cane corso may not be a possibility and they may not have the equipment. They may not have the um support staff to be able to do that. And so they may be making that recommendation based on what is appropriate for their particular clinic.

[00:21:46]Um maybe you have a large breed dog where they want to have that spay done um and a gastropexy at the same time.

[00:21:53]They may have to um refer you. And so those are definitely conversations to have. And um one of the reasons why they may recommend spaying your dog a little bit earlier. Again, we're not talking about pediatric. We're talking about earlier in that 9 to 18 months may strictly be a size situation. Um, spaying a small dog from personal experience, having literally been in there is much easier and much more enjoyable than doing a very large, obese, overweight, lots of um, internal atapost tissue becomes very difficult.

[00:22:24]Um, I have had dogs, adult dogs that I have spayed, um, that there is so much intraabdominal fat that I have to change my gloves several times during the procedure because the amount of literal oil and grease from doing that procedure is a lot. Um, and when there is oil and grease and slippery and lubrication, complications can happen. So, liatures can slip, which can lead to postoperative bleeding. And so, the larger a pet is, the more post-op complications you're going to have. the incision's going to be um a lot longer.

[00:22:54]The recovery is going to be a lot longer. Um you're going to have more complications as far as postoperative bleeding and things like that. That is not the function of the surgeon. Even the best surgeons anatomically are going to have a little bit more trouble um or a little bit more complexity when spraying a large breed dog that is um you know fully mature and at mature weight. Now, another bonus tip here is if you are going to wait, let's keep those dogs um in a good body condition.

[00:23:21]And so overweight, obesity is going to be a major complication there. And so if you are going to do the spay later in life, you're going to shoot for more of that 18mon mark. Then let's keep them lean because that's going to make the posttoperative surgical complications a little bit less. The bigger they are, one thing that people hate are those cones. The larger they are, the larger that cone is going to be. Yes, a cone is necessary or potentially a surgical suit if you can find one large enough because yes, I have had um horror stories where the cone came off or there was no surgical suit and the dog chewed open their incision and actually chewed internal organs and you can imagine how that sad story played out. And so, um yes, that is another thing to consider.

[00:24:05]There are a lot of people where having a ginormous cone in the house because they have small children or elderly is just not um feasible. And so those are some of the, you know, other things that we as a vetinarian that maybe are not in the forefront of your mind, but we know because we see them more regularly and there's no literature about them, but we know increased cost, falling off the radar, not wanting to do the cone, post-operative complications, those things do go up um you know, the bigger and larger um the dog the dog is. And so that's kind of the workflow or the thought process um given the current literature on canine um neutering and spaying. Obviously things are always changing and there isn't necessarily a wrong a wrong answer. Again it's individual. It's conversations that factor in all of these things that you are going to be discussing with your vetinarian. If your pet was spayed early or neutered early, it does not mean or does not guarantee that they are going to have orthopedic conditions. Um, if you do everything right and you do everything perfect, it does not mean your dog will not get mammorary cancer or your dog will not get um orthopedic issues when they get older. Okay? We're just talking about optimizing and we're trying to make the best decision. We're trying to make the best decision um in conjunction with your thoughts, your feelings, your budget, all those things.

[00:25:26]So, I hope that gives you food for thought um and um things to discuss with your vetinarian and opens that conversation, opens that dialogue. I look forward to your comments um below.

[00:25:38]So, we'll see you guys next time. Bye.