Good evening and welcome to our platinum webinar this evening. Tonight I'm delighted that we are joined by Professor Sandra Core of the University of Glasgow, and, Sandra will be exploring the topic should we routinely m to pets, dogs and cats, sorry. To date, for those of you who've joined us previously, you'll know this, the score.

So if you do have any questions, throughout the, webinar this evening, please do post them in the Q&A box at the bottom of the screen. And then at the end, we will have some time to, reflect on those questions and post them to Sandra. And if anyone can post one that, stumps her, then you'll get a special prize from, Anthony at the webinar vet, I'm Rich Daly.

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Professor Sandra C is a professor of orthopaedic surgery and head of surgery at the University of Glasgow School of Veterinary Medicine. Following graduation, she spent 6 years in general small animal and equine practise before completing a PhD at the Roslin Institute and a residency in small animal surgery at Glasgow University. She then worked at the Royal Veterinary College in London, gaining her ECVS diploma and at Nottingham Vet School before returning to Glasgow.

Sandra spends 50% of her time on clinics in referral orthopaedic cases. Her other interests include the human companion animal bond and ethical questions relating to keeping animals as companions. So without further ado, I'm delighted to hand over to Sandra, who'll talk about the topic of should we routinely neuter pets, dogs and cats.

Thank you over to you, Sandra. Hello, good evening, and, and thank you very much for joining me, on this webinar to, to discuss the question of should we routinely neuter pet, cats and dogs. And, I think at the start, it's, it's important to stress is that that the focus is on the individual animal.

So we're not going to, to talk about population control. I think that we, we'll all recognise and accept that neuting is an important part and an important aspect of. Controlling pet populations, stray populations.

We're really going to focus on the individual animal and review the literature, specifically looking at the medical benefits and the potential adverse effects of neuting the the the individual pet cat or dog. And I'm gonna talk very little about behaviour because we, we still don't really understand all of the, the, the aspects of, the effects of neutering on behaviour, and that, that probably would take a webinar in itself. So we'll we'll very briefly touch on that.

And I'm not gonna discuss the sort of philosophical or or ethical aspects of nutrient, although I, I do find them fascinating, you know, the question of of whether it's right to, to take away an animal's right to, to reproduce, if you like. But if you're interested in, in that sort of topic, and, and in the interest of disclosure, much of, of what I'm going to talk about this evening is, based on work done with two colleagues, Peter Sano, who's a professor of philosophy in Copenhagen, and Claire Palmer, who's a professor of philosophy in Texas. So, And we, we published a paper on this work, and, and we actually published a book on companion animal ethics in which we sort of addressed these types of questions.

So, in the interest of disclosure, I should probably also tell you that I have two cats, both of which I, I neutered when they were kittens. So there we go. OK, so the, the structure of the talk, we'll talk for the next sort of 50 minutes or so, about starting with the control of reproduction, and we'll look at the, the sort of perioperative surgical risks, and then we'll look at the, the, the longer term effects of of neuting cats and dogs, and that's where things get quite, quite complicated because the data is very, very messy.

There are hundreds of studies out there, and many of which produce conflicting results. So we're going to try and look at the data and the studies by dividing them into studies looking at the effects of females being neutered, we'll look at cats and dogs, then we'll look at the effects on male cats and dogs have been neutered. And then we'll try and look at potential age effects and then we'll look at some really interesting recent studies that look at the effects of muting on, on specific breeds.

So very much like, like human medicine where they're, they're turning towards what we call precision medicine. And rather than treating sort of the the human population as a sort of generic population, they're they're starting to look at individuals and individuals with specific diseases rather than than lumping everyone together. And I think maybe one thing that's coming out of the evidence on neutering is that maybe we have to start thinking of our dogs and cats in a, in a similar way.

OK, so, I'm presuming everyone out there is a vet, so I'm, I'm rather lecturing to the, to the people who already know this, but if we think about how we can control reproduction, we can do it in a, in a temporary non-surgical way, or we can do a permanent surgical ne. So, my, my philosophy colleagues like to say that the abs abstinence is always possible and to a certain degree, it is possible to keep your dog on a lead, and it is possible to keep your cat indoors, but, but realistically, it's, it's not a foolproof or a or a long term solution. In animals that we might want to use for for breeding, or in animals where we want to test the effect of, of nuing without doing a sort of permanent surgical nutrient, we can try various types of, of chemical sterilisation.

The difficulty with, with that, there's, there's still the concerns over potential adverse effects, but largely it's the, the effectiveness, the, the reliability and the cost of, of, of chemical sterilisation, and you know, owners have to remember to take the dog to have the injections or they have to remember to give the tablets or have the, the vaccine administered. So as a long term solution, it's, it's not necessarily very, very reliable. So, in most, most sort of countries such as the, the US, the UK, many of the veterinary associations promote permanent surgical neutering as as being responsible pet ownership.

Now, that's not, not the case across the whole world. So there are countries in, in Europe where they take a very different attitude, and many Cats, for instance, in Italy, pet cats are not neutered, and it's actually illegal in some European countries to castrate a male dog for that doesn't have a good medical justification for doing it. So, although it's still the, the sort of majority opinion in most parts of the world, there are certainly countries that are are taking a bit of a different perspective on it.

Nonetheless, if we're going to permanently neuter our our pets, we have a number of choices. So in females, we can perform an ovarian hysterectomy where we, we got to take out the ovaries and the uterus, or we can do an ovarectomy where we're just going to take out the ovaries. And we have the option, certainly in dogs of doing this as an open procedure or endoscopically.

And then of course in male animals, we, we have the, the castration is the standard procedure. And in male dogs, sometimes people will elect for a a a vasectomy. Any kind of surgery has risks.

So, even although neuting is very routine, if we start by thinking about the actual surgical procedure and the, the, the potential morbidity that that might cause the animal. As you'll know yourselves, we can, we can divide any kind of surgical risks into minor risks. So we have things like a little bit of wound inflammation, a little bit of reaction, or we can have fairly major complications, particularly with nutrient bleeding is always going to be at the top of everyone's list.

Even with sterile procedures, clean surgeries have an infection rate, perhaps about 5%. And occasionally we'll see a wind breakdown or if things go very badly wrong, and animals can die following relatively routine procedures. And it's a little bit of an old study now, but it, it, it's a study done by Polarial who looked at and basically the mortality rates in animals, dogs and cats undergoing general elective surgery.

Now this is not specifically neutering any kind of elective surgery. So these animals are fundamentally healthy, and they report these postoperative complication rates of between 6 and 19% of dogs and 2 and 12% of cats, but most of these were minor and out of Over 1000 dogs and 1500 cats, really they only saw major complications in 7 cats and 7 dogs. So really not, not terribly high major complication rates.

OK, if we think specifically of neutering, if you're like me, I don't think there are many vets out there who, who don't remember the fear that their first bitch stay instilled in them, especially if it was a very fat bit space, so. Even though still teaching veterinary students, the, the thing they all fear the most is there, is the first bit that they have to do on their own. And obviously the, the biggest concern is, is the, the, the fact of, of bleeding, you know, of tearing an artery, tearing a, a vessel in the broad ligament.

And so we can have bleeding either from our ovarian pedicle, which is the most common end, or from the uterine artery. And you can see a lovely illustration on the, the side here, which is, that's just to, that's for dramatic effects. That was not after a a a beach day, that was actually after a hemoabdomen, but I, I think you get my point.

In a small number of cases, there's also the risk of ovarian remnant being left behind. The, the, the broad ligament is very tense and sometimes, as you can see here, your forceps are very, very close to your ovarian bursa. So I think the, the rule is always to open up that bursa and have a look before you close up.

Just make sure that you haven't caught a little bit of the edge of the ovary and left it behind. Study, interesting study suggests it's much more common to leave a bit of the right ovary behind for some reason. And obviously you will then have an animal that potentially will come back into season, and it can happen as quickly as 2 weeks or in some cases it's been reported up to 9 years later.

So if you're going to go back and have a look, you're, you're more likely to find the the little bit that's left behind if you do so when the animal is in in season. And, and then the, the, the really sort of bad complication is if you, you unfortunately managed to ligate a ureter when you're doing the stay and, and that, that's very, very rare, but it's a little bit more common if the bladder is very full at the time. So I think that the top tip there is to make sure your bladder is expressed before you, you spray anything.

And then the, the, the complications you see less commonly now, stump pyometers do occasionally happen, but the sort of fistulous tracts that, that we used to see if people used a lot of chromic catgut, I think that's very, very rare now. So if we look at complication rates specific to neutering, we've got a couple of studies here and if you like, they're at the opposite ends of the spectrum. So there's a nice study in 2005 looking at ovarian hysterectomy in which is done by.

Your vet students and the overall complication rates seemed reasonably high, about 20%, 6% lead, and then we had about 14% of other complications, but none of them were major, and none of the animals died. Then at the other end of the spectrum, a more recent study looked at the complication rates in a high volume neuter clinic over a period of six years. So you can see there's a, a, a very large number of cats and dogs being neutered there, and they found a, a, a mortality rate of 3.3 animals per 10,000 dogs.

So that's, that's very low as you would expect. Excuse me, but what I thought was was very interesting is they found that the risk of mortality was 5 times as high in cats as dogs, which, I don't know about yourselves, but I, I find that quite surprising because I always think cats are, are easier to neuter than dogs, but also the risks of mortality were twice as high for females as males. So perhaps that's that's less surprising and and a bit more predictable.

OK, so, a little poll question to start with. It's interesting. I would be interested to know in dogs, do you perform an ovarectomy or an ovarian hysterectomy?

OK, so I've launched the poll question. So if people can answer either A ovarectomy or B ovarian hysterectomy, I'll just give you 10 seconds to answer that. So no right or wrong answer.

It's just interesting to get your thoughts so Andrea can continue the conversation. I'll give you another 5 seconds. OK, I think that's everyone that's answered there, so that's fantastic.

I'll just send the polling. And so 36% have said ovarectomy and 64% have said ovario hysterectomy. Over to you, Sandra.

OK, that's interesting. I'm gonna ask a second question, and what do you do in cats? OK, and I'm just launching that one now.

So once again, A or B. A is ovarectomy and B is ovario hysterectomy. Give you another 5 seconds.

Couple more people left to vote. Mm, OK, we'll end up there. And once again, very similar numbers, 40% have said A and 60% have said B.

OK, so that's that's, I think, predictable. I that that's the kind of result I might have expected and it's, it's interesting because the evidence so far suggests that certainly in dogs, there's no clear advantage to removing the uterus and ovarectomy is a, is a more straightforward and less invasive surgery. And I think what what worries people is that, you know, if you leave the, the uterus behind, there's a risk of uterine disease, obviously, but I think that the thing to bear in mind is if you don't have any hormonal influences, then risk of things like pyometra, very, very, very small.

So it's a, it's a bit of a balance. OK, so, next question, surgical approaches in cats. Do you use a flank approach or a midline approach?

Keeping me on my toes with these poll questions tonight, Sandra. So again just launching the poll questions. So, in cats do you use a a flank approach or B a midline approach you'd like to, put in your quick answers now please.

Fantastic, just 5 more seconds to give everyone else the chance to vote. Brilliant, and I will end the polling now. And the results are, 58% have said A, the flank approach, and 42% have said B, the midline approach.

OK, so that's, that's interesting, probably about half and half. A couple of years ago, about 90% of people would have used a, a, a flank approach. And again, in a, in a little study on vet students doing this, it's, it's perhaps predictable that.

The flank approach what students and and I think people in general find more difficult is getting into the into the abdomen through the peritoneum. But in the midline approach, what people struggled more with was was finding the uterus. So in the study, in terms of of complications or time, etc.

For the surgery. There wasn't really any significant difference, but, the, the flank approach seemed to create a little bit more of a, a problem with incisional discharge. So cats pade through their flank tended to have a little bit more discharge from their, their wounds.

OK, and the last sort of whole question for the moment is, increasing numbers of people are are are are staining animals or staining dogs, bitches through laparoscopic approaches and I'm interested to know how many people are doing that. OK, so just launching the poll question again. So if you routinely perform via an open approach, please indicate A, or if you perform a laparoscopic approach, please indicate B.

OK. Just give me 5 more seconds to answer that. OK, it looks like the answer to this one is slightly more one-sided, Sandra, with 92% of people saying they go for the open approach with and 8% saying they take the laparoscopic approach.

OK, so great. I, I think that was again entirely predictable. Not a lot of evidence yet, but I think if you, what we do know is, is fairly predictable in that laparoscopic space or lap space, there's quite a steep learning curve, and they do tend to take Longer, but a couple of studies have suggested that animals that have had a lapse, they seem to be less painful afterwards, show less of a reduction in activity.

And so they suggest there are some treatment benefits to having a laps, as, as you might imagine. But when I, I discussed this with a, a, a, a general practitioner colleague, they, they laughed and they said, I bet I could get my bit stay done before you get all your kits sorted out. And I think that's, I think that's probably true.

OK, and then with males, obviously we, we have a a a a more limited approach to, to the surgical and neutering, and most people will do open or closed castrations, and very occasionally, we may choose to vasectomize male dogs, and if we are doing it purely for reproductive control, but I think as, as we all know, much of the time. We are neutering constrating male dogs to, to try and control their hormone-related behaviour. And it doesn't remove the risk of, of things like testicular tumours.

But, a little bit later in the discussion, we may revisit the idea of vasectomy when we talk about some of the potential adverse effects of, of castrating male dogs. OK, so the last thing we want to think about in the, in this kind of early part of the discussion of sort of perioperative concerns is the idea of of pre-pubertal neutering. Now, again, if we think about cats, you know, puberty usually 6 to 8 months, but they can get pregnant before that.

Dogs tend to be very variable and based on, on their size. So often, older and large breed dogs are, are, are a bit older and less predictable when they're going to have a season. So it's important that when we talk about pre-pubertal nutrient, we're talking about sort of 6 to 16 weeks.

We're not talking about early neuring, you know, neutering at 6 months or so. We're talking about much, much earlier. And this is something that's That's being fairly heavily promoted by charities because obviously they want to neuter the animals before they leave their premises or, or as soon as possible afterwards for the the the population control.

So interested to know how many, how many of you perform early neuting of dogs, cats, or both dogs and cats. OK, just launched the poll in for this pole here. So do you perform perform early nutrient of dogs, cats, or C, both dogs and cats.

So once again, A for dogs, B for cats, and C for both dogs and cats. Just give you 5 more seconds to answer that. As I say, there's no right or wrong answers just to give Sandra an idea of the approaches you take.

So, say A, B, or C. And we'll close that there. OK, so, it's interesting that no one has answered a.

60% have said B and 40% have said C. OK, that's, that's, that's really interesting. That's quite, quite a bit higher than I thought.

So, perhaps you'll find that interesting as well. Now, so far, in terms of short term risks, so kind of periocerative risks, and it seems that there, there are very few risks associated with prepubertal neutering. So there's quite a bit of resistance because people thought, well, you know, is it, is it going to be a more difficult surgery?

Is it going to be a greater anaesthetic risk? But so far the studies are suggesting that the complication rates are lower. And the surgery is quicker and they bleed less and there really is no increase in the anaesthetic risk.

So in terms of, of potential risks of this prepubertal neutering associated with surgery, it seems that there are, there are minimal risks and, and, and significant benefits. OK, so, so far, the evidence is, is quite clear in terms of perioperative risks and benefits around neutering. We, we, we have a, a greater risk of morbidity and mortality in females and males.

We have a greater risk in cats and dogs, and we seem to have less risks and more benefits of, of prepubertal nutrient compared to nutrient when they're older in terms of the sort of short term and periooperative risks. So we'll move on now to the, to the potential long term benefits and and adverse effects and, and this is where it gets a lot more complicated. And I think what we'll do is we'll start by admiring how beautiful Scotland is.

So this is a little moment of reflection to to, to suggest that anyone out there who would like to come and visit Scotland, you really should, it's beautiful when it stops raining, which it hasn't for quite some time. OK, so let's think about the, the longer term effects. So we're gonna look at the data, as I said, we're going to first of all, consider female dogs and cats.

We'll look for differences between the two, and then we'll look at male dogs and cats, and we'll look at differences between the two. And it's important when you review literature to look for flaws or look for things that haven't been well controlled. And one of the problems we have with the literature, and one of the reasons that the results are often very conflicting, is that when we divide our groups of females into neutered versus entire.

We don't know whether the entire animals were bred or not, and that makes, potentially makes quite a significant difference. So that that may be part of the reason why sometimes the results seem conflicting. OK, so if we start with female dogs or, or bitches, some very obvious things.

So obviously, if we neuter our bitches, we're gonna prevent pregnancy. We've said we're not going to talk about population control, but in terms of preventing pregnancy, we're gonna avoid some of the risks associated with parttuation and some of the illnesses that that dogs can develop when they're pregnant and obviously things like diabetics are much more able to be better controlled if they're not going through seasons. And we can prevent pseudo pregnancy, which is, you know, can be quite prolonged and, and frustrating for the owners if, if not for the dogs.

And one of the commonest reasons that people will recommend spaying on nutrient bitches is to prevent pyometra. Now, the earlier study I've, I've put down there reported up to 15% of entire bitches as as developing pyometras quite early on, and I think more recent studies have suggested this is not the case. So this was a, the Fukuda study and it was basically involved experimental beagles, so it's perhaps not that representative.

And more recent studies such as my heart to tell that suggested that really pyometra incidence in in entire bites is, is not as high as we may have thought. And the other reason that's often given for neuting bitches is, is to prevent mammary tumours. Now, some of the, the later studies looking at different breeds showed quite interesting differences in tumour development between neutered and entire dogs.

So we, we'll come on to that later, but we'll address the, the question of mammary tumours here. So I think probably everybody would be familiar with the first study by Schneideral, which is the one that's often quoted as a good reason to neuter bitches before their first season. So the Schneider showed that if you neutered an animal before its first season, you reduce the risk of developing mammary tumours to less than 0.5%.

If you left it a little bit later, so between the 1st and 2nd season, it went up to 8%, and after the second season, 26%. OK. But, a more recent systematic review by Boves at all in 2013 reviewed a lot of the literature, including the Schneiderel study, and said, yes, there were, there were weak effects, but the studies weren't always really that well controlled.

And then the studies by Harteal in 2014 and 2016 showed that really neutering didn't seem to make a big difference. So if you have a look here, we've got golden retrievers, didn't find any mammary tumours in intact ones. And even when they were neutered between 2 and 8 years, the incidence was only 3.5%.

In German shepherds, slightly higher incidence in intact dogs, but not massively different in in neutered dogs, so they didn't find a significant difference. But then the study here by Houlihan actually did again so showed that entire females had a 3 to 7 times higher incidence of mammary tumours than neutered females. So they, they came out very much in favour of neutering as a as a prevention.

And in general in studies that electively neuter pictures, they found these countries reported a much lower incidence of mammary tumours. So I think that the evidence is in favour of neutering having a positive effect on reducing the, the, the incidence of mammary tumours. But the adverse effects, again, I think everyone will be familiar with is that the particular one is urinary incontinence.

So especially large breeds, we're going to see a higher risk of incontinence and according to thrashfield at all, the risk was increased 7.8 fold in, in, in uterine pitchs. And it's usually treatable, can often be medically managed, but up to 50% may require surgery.

And more recent studies, such as those by Haral started to look at the effect of age at neutering, and they found, as you can see here, that if you were neutered under 6 months, it's about 4%, if you neutered a little bit later, the risk increased. So netriing did have a significant effect that was influenced by age at neuter. The other thing we all know about is obesity.

So if we neuter our our bitches, they do tend to get fat if we're not careful. And we'll talk a little bit more about that when we talk about nutrient cats. Another interesting thing that you might often see is that sometimes we see changes in skin and hair coat in animals that have been neutered, and this study by Sandberg showed a significantly greater risk of some immune-mediated diseases which I've, I've listed here.

So interestingly, atopic dermatitis. Immune hemolytic anaemia, IBD irritable bowel, and hypothyroidism, and the, the odds ratios are shown there and basically the odds ratios are just showing that if you if you are a neutered male, you have 1.5 times greater risk of developing atopic dermatitis.

So if you look at the values apart from the hemolytic anaemia, neutrient of females. Gives them a greater risk than males. So neutering females are more at risk of these immune-mediated diseases.

And again, neutering increases the risk of joint diseases and some cancers in some breeds. So we're gonna talk a bit more about that later. OK, so balancing up the, the, the adverse effects and the potential benefits of the, the bitches and nutrient bitches will, will come at the end and we'll think what, what the jury decides about that.

OK, so if we think about female queens now. Pregnancy, same as bitches, and, and cats are more likely to to get pregnant because they're free roaming and they're outdoors. They're not on the end of a lead.

So that's a potentially more relevant concern. Diseases such as pyometer are less common in cats, but mammary tumours have got the same as, pictures. Although mammary tumours are rare, much rarer in cats, many, many more or much greater percentage of them are malignant.

And if you knew. Treat your cats at under 6 months according to over, you get massive reduction in the risk of developing these horrible mammary carcinomas that cats get. So there's a definite benefit to uterine cats in terms of preventing their their mammary carcinomas.

And the good news for cats is that you don't seem to see an increase in any urinary tract problems as a, as a result of, of neutering. So we don't have this urethral sphincter mechanism in confidence problem that we have in dogs. OK, but the bad news for cats is, cats of both sexes, if you neuter them, they are significantly more likely to become obese, OK?

And as a consequence, they're also significantly greater risk of becoming diabetic. And this is because oestrogen is a, is a major suppressor of an appetite in cats. So if we take away and remember testosterone partly metabolised into oestrogen.

So we, we have this effect in both sexes, but if we take away the oestrogen, we have an increase in appetite. And so neuting results in an increase in appetite and a reduction in metabolism, especially in females, and they also become less active. So we, we, we kind of have a triple whammy.

And the interesting thing is that studies have shown if you administer exogenous estrogens, you can, you can reverse this, so you can control the appetite by administering oestrogen. But the good news again is that we can't control it to an extent because we, we can reduce how much we, we feed them. But the, the, the main effect or the main sort of effect on health of cats is, is the obesity and the potential for, for diabetes.

OK, so male dogs, let's have a think about benefits and risks. So I said I wasn't gonna talk much about behaviour, but the main reason we neuter male dogs is because we're trying to control their behaviour, and it does affect to some degree. So, the first study there showed that reduces roaming and urine.

Parking makes some breeds more trainable. And the Gynatal study interestingly showed, however, the male dogs that were neutered were most likely to have bitten someone. OK, so you have to think back we said, we've really got to to think about the way these studies are controlled and in this guide test.

We don't know that the reason these dogs were neutered were was because they had bitten someone, you know, so they could have been neutered because they already bit someone rather than neutering, making them bite people, because most studies will suggest that actually more people are bitten by entire animals than neutered animals. OK, and I think you probably all are aware that if it's a particularly nervous aggression, uterine can actually have the opposite effect to the to the desired one. OK.

The benefits of, of neuting include reducing the risk of testicular disease. So it's quite common, 16 to 27%, but most types of testicular disease are relatively benign, and we can reduce the risk of the the androgen dependent diseases such as perinatal hernias and, and benign prostatic dyspla hyperplasia. So we've got, we've got some benefits there.

But in male dogs, and we also have significant adverse effects. So we get a significantly increased risk of prostate and bladder cancers which although they're rare, they are generally very highly metastatic, OK, so they're bad things to increase the risk of. And then we're seeing increasing studies that show that neutering male dogs increases the risk of other cancers with breed and age effects.

So as you can see there, neutering and Rottweilers less than 1 year old have a 1 in 4 lifetime risk of developing osteosarcoma, and that's significantly higher than entire dogs. And then early ne male golden retrievers can increase the risk of cancer such as hemangiosarcoma, lymphosarcoma. And we'll talk a bit more about that later and we'll talk about the effect on joint diseases in these dogs.

But I think the important thing here is that we're getting increasing evidence that actually we should be treating dogs as individuals rather than than sort of prescribing routine uterine because in the, in the days of sort of informed. Consent with owners becoming a little bit more litigious. You know, if you have an owner of a Rottweiler that develops an osteosarcoma, and, you know, we haven't maybe discussed the potential of that, are, are we gonna have owners starting to complain that they, they, they weren't properly informed about the risks of neutering?

It's just food for thought. OK, and then Tom cats. Same sort of benefits, prostate and testicular disease, but they're very rare in cats, not the same as as dogs.

And again, we won't talk much about behaviour, but arguably, it reduces the risk of fighting and roaming and certainly with urine spraying. So, you know, nobody really wants a male. Cat spraying all over the house, so perhaps their their welfare is not is not helped by that, and they have a better life if we're not always there shouting at them or throwing them outside when they're spreading on the furniture.

But the adverse effect significantly increased risk of obesity and diabetes. OK, and then longevity. So do neuter animals live longer?

OK, a lot of literature out there is sometimes quite con conflicting. So Relar study showed that they, they do live longer because there's a decreased incidence of disease. And a lower risk of behaviours, risky behaviours that might result in injury.

And also these, the, the argument is if you're a responsible quote owner that neutrals your pet, you're also more likely to give it better care in other aspects of its health. Hoffman's showed that in a study of over 40,000 dogs, so it's a huge study, and mean age reached by neutered dogs was 9.4 years and male and female, 7.9 years with the female for intact dogs, but the life expectancy and of neutered females was increased by 26%.

So that's a huge increase, and in neutered males by 13%. So again, huge increase from neutering. However, Zincatel showed that in this laws in particular, there was really no difference in longevity.

So again, it's coming back to this, can we have a one size fits all policy, or do we need to consider individual breeds? And then a huge study by the, the big band field pet sort of hospitals in the state, so a massive network of pet hospitals showed that neutral females typically live 23% longer and males 18% longer than sexually intact ones. So the, the balance of evidence seems to suggest that neuter animals do live longer.

And I think it's important to sort of reinforce again here that These studies are showing an association but not a cause. So it doesn't mean that if you neuter your animals, they will or won't get cancer or if you, you know, or they will or won't live longer because these, these cancers, longevity, very, very complex, multifactorial problems. You know, we've got genetics, we've got environmental factors, we've got body condition scores that we need to consider.

So what it's saying is there is a strong association between neutering and the things we're talking about, and not that neutering is, is a, a, a, a, a primary cause of, so I hope that's clear. OK, so then we'll move on to age now and again, just to, to clarify, really important in the studies is to recognise that age doesn't equal reproductive status. So a lot of, if we're talking about prepubertal neutering, so you know, down at the sort of 8, 16 week age, it certainly does, but when we're talking about animals neutered at 6 months, you know, if that's a small dog that may have had a season, if that's a large dog, it, it may, may not have.

So, very nice, a very large study on shelter kittens here. So they had 800 shelter kittens, 8 to 12 weeks old, randomly allocated to have a, a traditional neuter at 6 to 8 months or a prepubertal, which was done fairly immediately on these kittens coming into the shelter. And they followed them up for 28 months for the, the, the list of conditions shown there.

So one of the, the, the limitations of this study is that they've only followed them for 2 years. So things might be different if it had been 5 or, you know, 8 or 10 years. What they found was that 6.2% of the kittens died, but there was no difference between the groups, whether they were neutered early or at traditional age, and it was mostly related to infectious diseases.

And in the short term follow up and the long term up to 24 months, we found no significant differences in health problems between these two groups. So that goes to support our suggestion that early muting potentially in general, didn't seem to make or have a very adverse effect on these animals' health, at least up to. To 24 months.

But this was a very nice study because what the authors did was they were very honest and they did a study to find out how many animals they would have had to look at to find just a 2% difference in something like urethral obstruction, and they would have needed over 1500 in the. Puber group and 800 in the traditional group. So, it again, it's a very, it's a very honest study and it's basically saying that we, we didn't see a big difference in these kittens and cats up to 24 months, but we may not have had a big enough sample size to be sure.

OK, so we're, we, we'll look at a couple of other things related to early neutering. One is the effect on the urinary tract and the other is effect on the musculoskeletal tract. So, again, lots and lots and lots of conflicting studies out there, and I've tried to, to summarise them.

So some studies as shown there have shown that early neutering has an increased risk of urinary incontinence in dogs and cats and dogs who turned under 3 months of age. And an increased incidence of cystitis in female dogs compared to female dogs neutered after 5.5 months.

A couple of studies showed that bitches neutered prior to puberty had infantile vaginas, predisposing them to vaginitis, recurrent urinary tract infections, and dermatitis. And then 3 studies showed actually there was a reduced risk of incontinence in bitches neutered early. So this is what I mean about the, the literature being very, very confusing and conflicting.

And a systematic review by Boveau suggested that there is some evidence. Of an association of an effective age in the early neutral pitchs perhaps were at greater risk, but they concluded that the evidence of a relationship between neuterine and incontinence was, was weak. OK, so the jury seems to still be out on that.

In terms of early neuring effect on growth plates, which I love being an orthopaedic person, we know that an oestrogen and testosterone are necessary for growth plate closure. So if you neuter an animal, the growth plates don't close for a while, so they end up great cat here. With long legs and up until recently, we haven't really thought that there were any clinical adverse effects from that.

We knew their legs were longer, but we didn't really see a lot of clinical problems. However, Recent studies by de Rivera at the heart of suggesting actually we may be seeing more joint diseases in these early neutered animals. And you may in practise be familiar with these sort of overweight male cats that were neutered who, who managed to slip their epiphyses off their, their, hips.

And there's also a study suggesting that jogs with very, very steep tibial plateau angles which may or may not be related to to cruciate disease, and these are 14 times more likely to have been neutered at an early age. So there's a little bit of evidence creeping in there. And just a brief mention here is that because the evidence is so messy, a number of studies are being set up to try and, and look for a little bit more clear evidence, if you like, and, and Rachel Moxon is a, a PhD student that I co-supervised with Gary England down in Nottingham.

And Rachel works for guide dogs and So she set up a study to look at the effect of pre-pubertal neering versus traditional age neutering in the guide dogs because guide dogs are traditionally neutered and, and they traditionally have ovarian hysterectomies after they've had a season. But what they, they're finding is that sometimes this can interfere with their Training, so we set up a nice study where the pups will be randomly allocated to early nutrient versus traditional aged nutrient, and we're going to look at the effects of a number of things, their health and their trainability and their behaviour. So, so watch this, watch this space.

OK, so we're on the, we're on the the the home straight now and we're gonna look at the effects of breed because increasingly people are starting to realise that actually, as I've said before, there isn't necessarily a one size fits all answer to should we neuter our pet cats and dogs. And I'm gonna just mention three nice studies to finish with. That look at the effects of neutering in German shepherds, Labradors, and golden retrievers, very common popular breeds and good working dogs.

Again, a little proviso, within these studies, some of the individuals may be related, so, so, you know, we may have a bit of a confounding effect of that. OK, so German Shepherds, this nice study and by Harteal looked at 705 males and just under 500 females, and they looked at joint disorders, urinary incontinence, and cancers. OK, and they found with joint disorders that neutering significantly increased the risk, particularly of cruciate disease.

Cruciate disease incident, about 7% in intact males, and if they were neutered under a year, increased up to 21%, which is a, is a very, very high incidence of, of cruciate disease. I'm, I'm surprised by that. And they found the same in females that it went up from about 5% up to 17%.

With urinary incontinence, they didn't find it at all in intact dogs, and they found that they got a non-significant increase if the animals were neutered under 6 months, but neutering at Between 6 and 12 months increased the incidence to 7%, so it pushed up the risk of incontinence, but they didn't actually find any increase in cancers in either sex with neutering at any age. So what's the the Take home message that they gave from that. They said, really try to avoid neuterating German shepherds until they were over a year old.

OK, so that's maybe a message that that we can think about when, when we're thinking about what we should do with our German shepherds. In the next study, we have, golden retrievers and the Torres del Rivierta, the same group in California, they looked at 759 client-owned dogs, 1 to 8 years old, that were either intact or neutered so-called early at less than a year or late at over a year. So you can see that the numbers in each group there, there are a reasonable number of dogs.

But two things to consider. First of all, 8 years old, it's not that old. So if we're talking about cancers, we're talking about other potential age-related diseases like Some joint diseases, maybe, you know, if they'd followed them to 10 or 12 years old, we might have got different results.

And also the idea of early or late neutering, we, we don't necessarily know that all of those dogs had or had not had, had seasons. OK, that being said, you can see the, the diseases they looked at there, looked at hip dysplasia, cruciate rupture, and three types of cancer, liposarcoma, hemaiosarcoma, and mass cell tumour. I bet you're all dying to know what the results were.

OK, so have a look at that. So in male golden retrievers, I hope my pointer is working. We've got our three groups.

We've got intact dogs, Dark, we've got neutered early, the lighter grey, and then we've got neutered late, the slightly darker grey. And if you have a look at that there, hopefully you can see a pattern. OK, and the pattern is Really big increase in hip dysplasia, less so in cruciate disease, but in lymphosarcoma in these early neutered male golden retrievers.

OK, so these are the ones that are being neutered under a year old and we're seeing less of an effect if they're neutered at a slightly later age. OK, have a look at the females and see if you can work out what's going on there. OK, so females are a little bit more difficult to interpret, but if you look neutered early, we've really pushed our cruciate disease up.

OK, not as high as German shepherds, but certainly we've pushed it up from seeing none in the intact dogs versus manrosarcoma and mast cell tumours are increasing in our neutered late dogs. OK, so what does that mean? Well, they've suggested, oh, I've given that away, so they've suggested that in the male dogs, what we should do is we should delay neutering male golden retrievers until well after puberty, so we're neutering them late, so we're not pushing our diseases up as high, but with the females, it's a bit more complicated.

And they're saying, basically choose if you're early neuter them, you're gonna push up the risk of cruciate disease from about 0 to about 8%. But if you, excuse me, late neuter them, you, you risk pushing up the disease and or the incidence of certain tumours. Now, again, remember, we're not saying that that nutrient causes these.

These are complex diseases, but we're saying there's an association between, you know, early neutering male golden retrievers and the incidence of hip dysplasia, cruciate disease, lymphosarcoma. OK, and then the, the last study I want to look at is a is a really nice study by the same group and what they've done here is they've compared golden retrievers with Labrador retrievers, so very similar breeds, but they found really, really interesting differences. They looked at the same sort of range of joint diseases, so hip dysplasia and elbow dysplasia and cruciate disease.

But what they did then, which I think is really clever and relevant, is they grouped it into at least one joint disorder. So if they had any one of these, they got put in that at least one joint disorder because they, they figured, basically, it probably doesn't matter to owners whether they're Dog has hip dysplasia or elbow dysplasia, you know, it's, it's the fact that it's got a joint disease. And they did the same with their cancers there.

They combined lymphosarcoma, hemangiosarcoma, and mast cell tumours into having at least one cancer again, because maybe it matters or it's less relevant to owners which type of cancer it has. OK, so we're on the home straight, but these graphs are a little bit more complicated, so I'll give you a little bit of time to have a look and see if you can work out what's going on. So this is joint disorders in golden retrievers, and our incidence or a percentage of affected impact males and females was down around 5%.

So we've got our males in dark black and our females in grey. So have a little look at that and and see if you can work out what's happening. And this is what's happening in Labrador retrievers.

OK? Again, we've got our intact animals, about 5%, so it's kind of the same incidence in percentage of affected and intact goldens and Labradors. And then we've got our early neuting and we've got our sort of older.

See if you can can work out what's going on there. OK, so hopefully, what's apparent. Is that in terms of joint disorders, uterine at 6 months significantly increases the incidence of joint disease in both breeds, but much more markedly in golden retrievers than in Labradors.

OK, so there's our intact percentage of affected intact animals, and there's our male neutereds at 6 months, way up here, OK? And this effect becomes much less when they're older and it's affecting the golden retrievers much more than the Labrador retrievers. And then if we look at the same study, same dogs in terms of cancers, have a look and see if you can work that out.

And what we've got is we've got a kind of lower, about 3% of intact females with either lymphosarcoma mast cells or mast cell tumours, and their intact males are up about 11%. And that's your golden retrievers. And there's our Labrador retrievers.

OK. So again, they start off with fewer dogs being affected by any of these diseases and neutering, hopefully you can see, really hasn't had a dramatic effect except for one here, lymphosarcoma. So golden retrievers really neutering at any time from about 6 months onwards.

Increase the risk of these cancers in some cases to 3 or 4 times the amount that you would see in intact dogs in females, but in males, the dark, is really not a massive effect apart from lymphosarcoma here, which is a bit odd. But in Labradors, neutering had really very, very little effect at all. OK, so even within.

Two types of dogs that are very, very similar. We're seeing a, a very, very different consequence or association between neutering and both joint disease and, and cancers. OK, so I think again, hopefully what's coming across here is that we, we, we can't really have a one size fits all in terms of the effect of neutering on individual animal health.

OK, so here we are. I'm going to try and summarise this for you. So the, the question that we started with was really from an individual animal, medical health perspective, should we neuter?

So think about where you think these different categories should go. So I tried to stay quite vague. I've said yes, probably, probably not or no.

Oh, gone the wrong way. OK, so with pictures, I'm gonna say, yes, the evidence seems on balance to suggest that the medical benefits of neuting pictures outweigh the potential adverse effects. But maybe not for golden retrievers.

OK, for male dogs, the evidence seems to suggest that on a medical basis, we're actually probably put them at more risk of harm than we do benefit them by neutering. Female cats, probably it's in their interest, so they, they're at a risk of becoming fatter and and diabetic, but, free-roaming cats, high risk of pregnancy and associated diseases. So it's probably in female cats' interest to be neutered, and it's probably not in male cats' interest to be neutered, although obviously it makes a much better pets.

So from a sort of general welfare aspect, it, it, it can be argued that it does have benefits. Evidence is suggesting that ovarectomy rather than ovarian hysterectomy is probably appropriate. The jury is probably still out on the long term effects of prepubertal neutering, although perioperatively, there's certainly benefits in terms of increased safety and, and reduced surgery times, long term, we're still getting fairly variable reports.

And male dogs, we might want to start thinking about vasectomies rather than castrting them if we are interested in looking at the incidence of all of these different diseases and cancers that are affected by removal of the hormones. OK, so I think the answer probably is that it's, it's no longer appropriately to routinely recommend neutering, and if we do advise neutering in in individual cases, I think consent must be properly informed, OK? But in saying that, there is a lot of very conflicting evidence out there, and I think it is, I think it's unreasonable to expect practitioners to keep up with every.

Single paper that comes out, and I think that what we need as sort of veterinary associations is our, our, our associations or governing bodies trying to, to, to concentrate that evidence for us and and give us guidelines and I think certainly in the UK that's what the the the RCVS is is currently working on and to try and give us advice or to try and disseminate advice on what the current best evidence suggests. OK, so there's a, a, a lot of references there for anyone who is interested in in reading through that. And thank you for your attention at this time on Thursday evening.

Thank you very much for that, Sandra. That was, very interesting. And, I think, you know, the overriding thing that was coming across there, that there isn't one size fits all.

And I think from a couple of comments I've seen, there's been quite a lot of sort of variance in how people approach things. So, please do, post some questions either in the Q&A box or in the chat box. We do have a little bit of time, so I will ask Sandra some of those questions.

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So that is the housekeeping. So on to the questions and answers. Let's see who's been posting what.

So there's been a question here, from Pedro, who's asked the group, it's more of a question to the group, does anybody perform hysterectomies, mostly in large dogs. From your point of view, Sandra, how does that sort of, you know, balance with what you've been saying today? So sorry, was that hysterectomy, hysterectomies in large dogs, yeah, so the uterus and the ovaries.

I presume that's what he's talking about there. He says that there's a, a report by er Michelle Kutzler, about this procedure, a spade procedure that preserves the ovaries in female dogs. Yeah, I think, I, I think that's interesting and I, I, and I gave this talk, or a similar talk at WSAV and a member of the audience asked that, and so I had a chat with a number of colleagues and all of us are a little bit uncomfortable about that, leaving the, the uterus behind and and taking the ovaries away.

I have read much evidence on the benefits of that. I appreciate the, the idea of maintaining the hor hormonal influence from the ovaries. And it's not something I have direct experience of and it's not something I've seen widely reported in the literature.

So I, I, I have a little bit of a reservation about that until, until more is known. OK, no problem. So, obviously I think it is a, new, it's it's been recently developed and is a modified space procedure, so I think it's watch this space and see what further evidence comes from that really.

But be cautious. I wouldn't be recommending that. Interestingly, I spoke to Gary England who is .

One of the leading reproduction specialists in the country, and he, he had reservations and, and wouldn't be recommending that procedure. So I think, I think watch the space until there's an awful lot more evidence out there looking at the potential adverse effects of that over the the benefits. No problem, that's great.

I think, yeah, Pedro's saying that Gary had mentioned it to him, although he did say he, that not that he recommended it, so it's along with, he, he's, along with what you're saying there, Sandra. . Well, I don't think, I think that was it for questions.

I think you've obviously given people great food for thought. The, the webinar will be on our website within the next 48 hours for people to review, so they can come and have a look back at maybe some of the case studies with the German Shepherd and the gold, the Golden Retriever as well, just to, see, you know, to remind themselves of what the outcomes were and, you know, to be able to advise them on how to sort of approach things, in the future, but. First, thank you very much for joining us.

Thank you to Professor Sandrao for the presentation this evening, and we wish you all a pleasant evening. So thank you very much, everyone, and we look forward to seeing you on the webinar soon. Thank you for listening.

Bye bye. See you now, bye.