An Inconvenient Truth: On Obesity and Sterilization in Dogs

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Obesity and Sterilization

If you’re like me you were raised to think that all pets should be sterilized. Dogs and cats, you were reverently informed, require sterilization if they’re to live long, healthy lives. To fail to spay and neuter, goes the mantra, is to commit a cruelty against animal kind.

It only made sense to me. Dogs and cats can get cancers and other diseases in their reproductive organs. And animal overpopulation is the inevitable result of an intact reproductive system. Sterilization was the gospel of modern pet medicine. Praise be.

Enter the twenty-first century and its new-fangled ideas with respect to our dogs’ reproductive tracts. Suddenly it seemed we were hearing more about diseases related specifically to sterilization in dogs.

Hormone-related incontinence in females was the first such disease. One we immediately glossed over as the inevitable result of sterilization, one that’s a necessary risk of sterilization, veterinarians lamented. Then we learned about a few studies that identified an increased risk of certain cancers and orthopedic diseases in sterilized dogs. Could it be that sterilization was not incontrovertibly benign?

Despite these recent findings, the prevention of reproductive diseases remains a perfectly legitimate reason to spay and neuter. That’s what all veterinarians are taught in veterinary school and it’s widely regarded as the primary reason we recommend sterilization procedures like spays and neuters. But as we’re now learning, preventing reproductive disease isn’t necessarily a good enough reason to remove organs; not if those organs offer more benefits than they pose risks.

Here’s a quick rundown of the risks and benefits of letting your dogs remain intact:

Risks posed by reproductive organs: These include prostatic disease, testicular disease, and perineal hernias for boys. Most are highly treatable. For girls, pyometra (uterine infections) and mammary tumors are the biggest risk. All but the most aggressive mammary tumors are treatable, if caught early. Male behaviors like roaming, urine marking, and aggression are more likely.

Benefits of intact reproductive organs: Normal hormone levels may protect dogs from suffering from certain orthopedic diseases along with some cancers. In females, low sex hormone levels predispose them to hormone-related incontinence. On the behavior side, very recent work indicates that intact male dogs may be more socially adept. They may be less aggressive with other dogs and may experience less fear-based aggression in social interactions.

Then there’s the obesity issue.

As the 21st century dawned, it became clear that the US had a huge pet obesity problem. Since then, our dogs have continued to become so incredibly fat that we’re unable to even properly understand how they got that way. Sure, we know it’s because we’re feeding them more calories than they expend, but that’s a long way from the heart of it. What, exactly, has changed in recent decades, to account for the boom?

To be sure, it has a lot to do with how we feed ourselves and our families and the “food is love” culture we reside in. It also has a lot to do with the rise of the pet food industry and the proliferation of diets and treats it so effectively markets. But could there be another component we conveniently tend to overlook? After all, everyone knows for sure that spayed and neutered dogs are heavier.

There’s no doubt about it. The inconvenient truth is that dog sterilization leads to fatter dogs. This we know. No one disputes it. Whatever you think about all these new studies on sterilization and certain diseases, the reality is this: Intact dogs are much more likely to enjoy healthy weights.

Which raises several questions: a) Is spaying and neutering our dogs actually healthier for them? b) Have we been led astray in our thinking on this issue by our community’s desire to prevent pet overpopulation? c) Are veterinarians actually recommending what’s best for our individual dogs? d) Have we researched this issue well enough given our level of sophistication on so many other veterinary issues?

The answers: a) Don’t know. b) Absolutely. c) Probably not. d) Hell no.

As I see it, health and overpopulation are two separate issues and they need to be divorced once and for all. After all, sterilization is not required to achieve normal population levels. In fact, in Europe, for example, where spaying and neutering isn't common, there is no dog overpopulation problem (and, incidentally, a much reduced incidence of canine obesity compared to US dogs).

Indeed, we have to quit thinking that spaying and neutering is the solution and that overpopulation is inevitable otherwise. I mean, responsible Americans are completely capable of keeping their pets from breeding just like Europeans do. (Aren’t we?) Yet every time I raise the issue I get attacked by individuals claiming that I’m irresponsibly encouraging pet overpopulation by suggesting there may be alternatives to sterilization.

The way I see it, however, until we do stop talking about overpopulation and sterilization in the same breath, we’ll have to face the inevitable reality: Our dogs are fat and they’re destined to get fatter. Perhaps one day we’ll be able to look at this problem more dispassionately, but until then, I expect to continue to see more obesity-related disease in dogs than almost any other.