> 3. Hit by car. Unneutered pets are much more likely to escape randomly and get hit by cars. Even pets that normally do not run away from their owners.
Most people I personally know/knew didn't spay/neuter their pets when I was growing up.
I've seen animals do some absolutely bonkers crazy stuff while in heat. I know an intact female pet that literally broke a screen window to jump out said window in order to mate. This was a second story window, yes she jumped out of a second story window!
I want to preface this by saying: veterinary science is just that, a science. Your vet has spent their career, hopefully anyways, learning what the best veterinary minds know about veterinary medicine. And your vet is probably a whole lot more trustworthy than random comments on the internet like this one. But with that said, I agree completely with the above: citation sorely needed. Show me the data.
One of the first conversations I had with my vet was about when I could start running with my dog. There's a lot of conversation online about how you need to wait until growth plates fuse to avoid future health issues (or similar variations on the same theme).
Her response was, to paraphrase:
> This is all just folk wisdom. There's no proper scientific evidence to support that conclusion, and it doesn't make sense to me. What distance are you running? Do you think a wolf could run that distance at your dog's age? You know your dog, just pay attention to her; play it by ear, don't take it too hard, take it easier on harder surfaces like concrete, and get her used to running before pushing hard.
When she said that, something really clicked in my head. We're finally, finally starting to talk more about evidenced-based medicine when it comes to humans, but when it comes to animals... The plain fact of the matter is that much of veterinary medicine is really just our best guess at things. All of the problems that human medical research have are magnified substantially in the veterinary world, even if just because of how much more resource-constrained it is.
I'm having a really tough time coming up with hard numbers here -- I can't find anything at all from the US -- but I found a UK report from about a decade ago [1] that, adjusting for inflation and currency conversion, suggests that $230mm USD was spent in the UK on all veterinary research, with a heavy emphasis on agriculture over pets (extremely unsurprising!). Meanwhile, about $3bb USD was spent on human medical research [2], with about $866mm USD spent for cancer research alone[3].
Think about how many conflicting studies we hear about cancer risk in humans. Now imagine how much worse it would be with less than 1/10 the budget. And again, most of veterinary research is specific to agriculture, not pets, so now imagine how much more worse it would be if most of that research money was spent on treating other species in completely different environments, with no interest in how it relates to humans.
So again: veterinary medicine is a scientific field, and part of your vet's job is to keep abreast of the literature, and they can almost certainly do a better job of it than you or I. But if you've ever been hit by the thought "man, there is just soooo much we do not understand about human biology" or caught yourself saying "anecdata isn't the same as medical research"... when it comes to veterinary medicine, the situation is much, much worse.
The going joke is that everything we know was true for 8 beagles. Veterinary studies are often small in scale and not made of representatives of the whole population.
I don't feel like digging through PubMed to back up an assertion like "unneutered dogs are more likely to roam and get hit by car." At best I'll be able to give you a records-review type of study and it's a low quality of evidence. Also, trends don't mean that your specific animal is going to be the same. I work with an unneutered labrador patient who is never going to get hit by a car, and I have definitely treated neutered ones who have. This association, though, does have a basis in animal behavior and is familiar to vets who work in emergency rooms.
The level of evidence that suggests that neutering is positively associated with cancer is extremely poor. Yet, there are people running with it like it's 100%. Meanwhile, we have stronger evidence that spaying prevents mammary cancer and castration prevents testicular cancer.
Good on you for jogging with your dog. Be mindful of their limits, because they will hide pain. Keep them in athletic trim and you should be fine, in my opinion.
Oh to be clear, I think it's perfectly plausible (and even likely). You can boil the question down to "does smelling a female in heat lower impulse control in intact males", and, well, yeah, I can believe that without batting an eye. But it was a convenient place to make a larger point about the lack of good evidence in a lot of veterinary medicine, which I think is something we should talk more about (I'd levy the same critique against medicine for people, too!). Anyways, I probably should have been clearer in my original post, that my point was really: it seems completely plausible, but we need to be better about citing research in medicine and being explicit about corresponding confidence levels, and veterinary research is woefully under-funded.
I think my personal biggest complaint about the overwhelming prevalence of desexing in the US is that we're not really being honest with ourselves about why we're doing it. I would argue, based on my experience, (I realize the hypocrisy in using sociological anecdata immediately after complaining about medical anecdata), the vast majority of pet owners who desex their dogs do so out of convenience, and the vast majority of policy encouragements for it (eg: shelters requiring it or cities assessing 10x licensing fees for intact dogs) are done because most US dog owners aren't responsible enough to prevent unwanted pregnancies and have a horrible habit of abandoning unwanted litters. That's not to say that there aren't medical reasons; some of them are even on really solid footing (eg using spaying as a way to stop frequent painful false pregnancies), but I don't think most US dog owners are even aware of that being a thing, much less making medical decisions in response to it.
I think we are starting to see a discussion of sterilization vs desexing, which is great, but even so, as it stands today, spay/neuter is standard practice in the US. I almost never see an acknowledgement that, particularly for females, we've more or less mandated a very substantial, very invasive medical procedure, mostly just because dog owners in the US just don't want to deal with a particular part of canine biology. And I personally think that raises ethical concerns around treatment of animals.
Also, thanks! She's an almost-90-pound ridgeback, so... running is one of the few things keeping us (relatively) sane!
I suspect a study to prove the exact means of connection is very difficult.
A retrospective study would be easier. Based on a survey of a given vets files (not quite a random sample, but for this case it might be good enough to establish a bias in facts), could trace the incidence rate of 'yard escape injuries' between 'intact' and neutered males, as well as 'intact' and spayed females.
I've seen animals do some absolutely bonkers crazy stuff while in heat. I know an intact female pet that literally broke a screen window to jump out said window in order to mate. This was a second story window, yes she jumped out of a second story window!
So I don't doubt it for even a second.