Spaying, Neutering, and Cancer: The Controversy

A week or so ago, a retrospective study on the effects of spaying and neutering on age of onset of cancer and behavioral disorders in Vizslas was published in the Journal of the American Veterinary Medical Association. This study suggests that, in the Vizsla (which is a relatively-uncommon purebred dog), the risk for developing certain cancers and storm-phobias is significantly increased if the dog is spayed or neutered. This follows a similar study in Golden Retrievers published last year which showed an increased risk of certain cancers and orthopedic conditions in dogs which have been spayed or neutered. Both of these studies were peer-reviewed (the gold standard), and in my opinion, properly done, and should be taken seriously.

Understandably, there has been a bit of an uproar calling for "us" to stop, um "mutilating" our pets with these horrible procedures (spays and neuters) which rob them of their reproductive organs and make them get cancer and other debilitating diseases. I am not trying to belittle these concerns, but before we rush to judgement, we might want to gather more information. I own two Golden Retrievers, and I want them to live the longest, healthiest lives possible. For that matter, I want all of my patients to live the longest, healthiest lives possible!

There certainly appears to be some serious disadvantages to spaying and neutering, at least in Vizslas and Goldens. (Note: these studies also suggest that early-age spay/neuter may increase the risk even more.) Another study suggests that neutering male dogs can increase the risk for prostate cancer. However, when we look at life expectancy (which is kind of important, wouldn't you agree?), the picture is a little different. The Golden Retriever study did not look at life expectancy, and the Vizsla study showed no difference in life expectancy between spayed/neutered dogs and intact dogs. So even though the S/N dogs were getting more cancer, they were getting less of something else - which made it a "wash." A more comprehensive study, looking at ALL dogs and cats (purebred and otherwise) was also published last year. There were 2.2 million dogs and 460,000 cats in this study. In this one, they looked at life expectancy in S/N pets versus intact pets. Guess what? S/N dogs of all breeds live 15% longer, and S/N cats live about 50% longer.

Does this mean we should mindlessly continue to recommend spaying and neutering all dogs and cats? Or should we crucify those who advocate spaying and neutering? Well, I for one don't want to judge anyone. There is still a lot to learn, and as more studies become available we will know more. Society (including companion animals) has benefited tremendously from the S/N "movement." How? Since routine spaying and neutering of pets has grown in acceptance (starting around 1970), the euthanasia of unwanted animals in shelters has declined from 24 million to 4 million. As a guy who "moonlights" at an animal control facility, I can tell you that's huge.

I will not bore you by listing all the benefits to the individual pets from spaying or neutering, although I've already mentioned the longevity study. But they are there, and they are documented. At my practice, we are keeping an open mind. Maybe we will be doing vasectomies and hysterectomies (a spay is an ovariohysterectomy, and a neuter is a castration) some day. But please be assured that we want very much to do what's best -we will recommend for your pet what we would do for our own.