Another Scientific Study Challenges the Wisdom of Government-Mandated Spay/Neuter



By: Phil Guidry, Senior Policy Analyst, AKC Government Relations


An article published in the February 1, 2014, edition of the Journal of the American Veterinary Medical Association (J Am Vet Med Assoc 2014; 244: 309-319) reported on the findings of an investigation into how dogs’ age at sterilization, specifically via traditional practices of gonadectomy—the surgical removal of a female dog’s ovaries or a male dog’s testes—impacts the risk of diagnosis of certain cancers and behavioral disorders in Vizslas. Other scientific studies are also underway seeking better understanding of the impact of spay/neuter on various aspects of dogs’ health, including the longevity, cancer resistance, and joint diseases. In the Vizsla study, the data were compiled over the course of 16 years via an anonymous online survey of owners.  Generally, the study found that, compared to sexually intact dogs:

  • Dogs sterilized at less than six months of age, between seven and 12 months of age, and at over 12 months of age had significantly increased odds of developing mast cell cancer, lymphoma, all other cancers, all cancers combined, and fear of storms.
  • Females sterilized at up to 12 months of age, and males and females sterilized at over 12 months of age had significantly increased odds of developing hemangiosarcoma.

The study further found a positive relationship between the age of sterilization and the age of diagnosis of biological and behavioral issues.  The younger the age at which a dog was sterilized correlated to an earlier average age of diagnosis of mast cell cancer, cancers other than mast cell, hemangiosarcoma, lymphoma, all cancers combined, behavioral disorders, or fear of storms.  When compared to the odds of sexually intact dogs, dogs sterilized younger than six months of age were also found to have significantly increased odds of developing a behavioral disorder. The study's authors call for additional studies on the biological effects of removing gonadal hormones and on methods to render dogs infertile that do not involve the full removal of organs that produce important hormones, including vasectomy versus castration for males and hysterectomy versus oviohysterectomy for females.  They also call on veterinarians to discuss the benefits and possible adverse effects of gonadectomy with clients, giving consideration to a dog's breed, their owner's circumstances, and the anticipated use of the dog. The American Kennel Club promotes a balanced approach to the issues surrounding spaying or neutering. We encourage pet owners to spay or neuter their dogs as a responsible means to prevent accidental breedings resulting in unwanted puppies.  However, the AKC opposes laws that mandate the spaying or neutering of purebred dogs.  Ultimately, we believe that all health care decisions, including whether to spay or neuter, should be made by a dog’s owner in consultation with their veterinarian.  The new insights provided by the Vizsla study provide further evidence that gonadectomy, like other major surgical procedures, should not be entered into without consideration of long term health impacts and should never be arbitrarily mandated by a government entity.