In the 1970s, a time when tens of millions of unwanted dogs were being euthanized in the United States annually, an orthodoxy began to take hold: Spay and neuter early. Spay and neuter everything. It’s what vets were taught. It’s what responsible pet owners were told to do.
A growing body of research, however, suggests that spaying and neutering—especially in some large breeds when very young—are linked to certain disorders later in life. “As time has gone on, vets are starting to question the wisdom,” says Missy Simpson, a veterinary epidemiologist with the Morris Animal Foundation, which recently published a study that found higher rates of obesity and orthopedic injury in golden retrievers that had been fixed. Other studies have linked early spaying and neutering to certain cancers, joint disorders, and urinary incontinence—though the risks tend to vary by sex, breed, and living circumstances. As such, the American Veterinary Medical Association (AVMA) now says in a guide for veterinarians, “There is no single recommendation that would be appropriate for all dogs.”
And yet anyone adopting from a shelter is unlikely to be told of these risks—or even to be given a choice. Today, according to the AVMA, 31 states and the District of Columbia require sterilization or a promise of such before pets can be adopted out of shelters. The American Society for the Prevention of Cruelty to Animals (ASPCA) also advocates early spaying or neutering of all companion animals at two months or two pounds in weight. Its information page for pet owners touts the very real benefits of the procedures—behavioral changes, fewer uterine infections, a decreased risk of certain cancers—but with nary a mention of possible downsides.