At What Age Should Your Dog Be Spayed/Neutered?

For decades, early spaying and neutering was common practice. But is there any reason to wait?

Researchers led by Dr. Benjamin L. Hart at the University of California conducted a detailed study that evaluates incidence of cancer diagnoses and joint problems in one breed (Golden Retrievers) by neuter status: early (before 12 months old), late (12 months or older), and intact. Consistent with previous studies on the topic, the results showed increased likelihood of hemangiosarcoma, lymphoma, mast cell tumors, and canine cruciate ligament (CCL) rupture in neutered dogs. 

The most profound observations were in hip dysplasia in male dogs when comparing early and late neutering. The risk of development of hip dysplasia doubles, and disease occurs at a younger age in the early-neuter group compared to both the intact and late-neuter group. No occurrence of CCL disease was observed in intact male or intact female dogs, or in late-neutered females. In early-neutered dogs, the incidence of CCL was 5.1 percent in males and 7.7 percent in females, suggesting that neutering prior to sexual maturity significantly increases a dog’s risk of developing CCL disease. With respect to cancer, cases of lymphoma were 3 times greater in the early-neutered males.

For the past several years the veterinary community has been aware that early-spay and neuter may impact orthopedic health in dogs. Through a very detailed analysis and inclusion of body condition score as a risk factor, Dr. Hart was able to show that timing of spay and neuter does indeed have health implications. Worth considering, however, is the fact that gaps in knowledge continue to exist concerning the complex relationship between sex hormones and cancer.

Generally speaking, it is with the above details in mind when we here at Windsor Animal Hospital recommend altering your pet no sooner than one year of age. When adopting a pet from a shelter that has an early spay and neuter policy, or if you are purchasing a puppy from a breeder requiring the alteration to be done early, we do offer signed letters from our doctors in an attempt to have your pet granted exemption until at least twelve months old.

The study, “Neutering Dogs: Effects on Joint Disorders and Cancers in Golden Retrievers,” is available online through the open access journal PLOS One. The work was funded by the AKC Canine Health Foundation with sponsorship from the Golden Retriever Foundation, Schooley's Mountain Kennel Club, the Siberian Husky Club of America, and the Vizsla Club of America Welfare Foundation.

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