When to neuter or spay your dog: New guidelines for 40 breeds

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Researchers at the University of California, Davis, have updated their guidelines on when to neuter or spay 40 popular dog breeds.

Their latest paper in Frontiers in Veterinary Science adds five new breeds to a research project that began in 2013.

This research started with a study showing that early neutering of golden retrievers could increase their risk of joint diseases and certain cancers.

This initial study sparked much debate about the best age to neuter other popular breeds. Professors Lynette and Benjamin Hart from the School of Veterinary Medicine, the lead authors of the study, decided to expand their research.

They examined more than a decade of data from thousands of dogs treated at the UC Davis veterinary hospital. Their goal was to give dog owners more information to make the best decisions for their pets.

The researchers specifically looked at the connection between neutering or spaying a dog before one year of age and the risk of developing certain cancers and joint disorders.

These cancers include those affecting the lymph nodes, bones, blood vessels, or mast cells. Joint disorders of interest include hip or elbow dysplasia and cranial cruciate ligament tears.

Joint disorders and cancers are particularly important because neutering removes sex hormones that play key roles in vital body processes, such as the closure of bone growth plates.

In their most recent study, the researchers focused on German short/wirehaired pointers, mastiffs, Newfoundlands, Rhodesian ridgebacks, and Siberian huskies.

They collected data from the UC Davis veterinary hospital’s records, covering more than 200 cases for each of these five breeds weighing more than 20 kg (44 pounds), from January 2000 to December 2020.

The Harts emphasized the importance of personalized decisions regarding the neutering of dogs, considering the dog’s breed, sex, and specific circumstances. They created a table with guidelines based on their research findings for all 40 breeds studied, including the five new breeds.

Health risks vary among breeds “It’s always complicated to consider a different approach,” said Professor Lynette Hart.

“This is a shift from the long-standing practice of early spay/neuter by six months of age in the U.S. and much of Europe. However, it’s important to consider these new findings about the connection between early spay/neuter and potential health concerns.”

The study found significant differences among the breeds regarding the development of joint disorders and cancers when neutered early.

Male and female pointers had increased joint disorders and cancers; male mastiffs had more cranial cruciate ligament tears and lymphoma; female Newfoundlands had higher risks of joint disorders; female ridgebacks had higher risks of mast cell tumors with very early neutering; and Siberian huskies showed no significant effects on joint disorders or cancers.

“We’re committed to improving the relationship between people and their pets,” said Benjamin Hart, distinguished professor emeritus. “This guidance offers information and options for veterinarians to give to pet owners, who should make the final decision for their pet’s health and well-being.”

Other researchers involved in this UC Davis study include Abigail Thigpen, Maya Lee, Miya Babchuk, Jenna Lee, Megan Ho, Sara Clarkson, and Juliann Chou from the School of Veterinary Medicine, and Neil Willits from the Department of Statistics.