What is the Best Age To Neuter Your Dog?

Lori Ennis
by Lori Ennis
A new study from researchers at the University of California, Davis looked at 35 dog breeds and found that some dog breeds have higher risks of developing cancers and joint disorders if they are spayed or neutered before they are a year-old.

Dr. Benjamin Hart is a distinguished professor emeritus at the UC Davis School of Veterinary Medicine. He said that when it comes to the best age to spay or neuter a dog, there is no one-size-fits-all approach.

Looking at 15 years of data over the course of the 10-year study, the researchers found that some breeds developed problems if neutered ‘early’ while others didn’t, and some developed joint disorders or cancer, but others didn’t.

The study was published in the Frontiers in Veterinary Science journal and examined 35 breeds. Previous research looked at limited numbers of breed groups.

Related: Japanese Officials Look At Spay And Neuter Options For Island Overrun With Cats

The data came from the UC Davis Veterinary Medical Teaching Hospital, and the team of researchers looked to see if a dog’s age at neutering, their breed or even their sex affected certain joint disorders and cancers. The cancers included lymphoma, mast cell tumors, osteosarcoma (bone cancer) and hemangiosarcoma (blood vessel wall cancer). The joint disorders included hip dysplasia, elbow dysplasia and cranial cruciate ligament tears.

They found in most breeds, the age a dog was neutered didn’t necessarily affect the risk of developing cancer or joint disorders. They did, however, find that there was a vulnerability to joint disorders in dogs that was related to their body size. Dr. Lynette Hart is a professor at the UC Davis School of Veterinary Medicine. She said that smaller breeds didn’t seem to have joint disorders, while a majority of the larger breeds did. Surprisingly, two large breeds–Irish Wolfhounds and Great Danes–showed no increased risk to joint disorders despite any age they were neutered.

They also found that in smaller dogs, cancer was less occurring and that was the case despite the dogs being neutered or not. Two smaller breeds, however, the Boston Terrier and the Shih Tzu, did have a significant increase in cancers with neutering.

Additionally, the sex of a dog made a difference sometimes when it came to their spay/neutering and health. Female Boston Terriers who were spayed at six months (a standard) didn’t have any increased risk of cancer or joint disorders when compared to intact dogs. Contrastingly, male Boston Terriers who were neutered before they were a year-old did, and in significant numbers.

Previous research has suggested that spaying female golden retrievers at any age increased the risk of them getting one or more of the cancers from 5% to 15%.

In the United States, dog owners typically choose to spay/neuter their dogs in order to reduce pet overpopulation. In fact, it’s often a requirement when adopting dogs from shelters or rescues, and typically is done by the time the dog is 6-months-old.

Related: Scientists Propose New Non-Invasive Spay And Neuter Procedure

The study suggests that the timing is something pet owners may want to think about, when considering their dog being neutered, and that the decision to spay or neuter should be made with your vet and your pet’s best health interests and not what society expects you to do. That may be easier to do if you’re adopting from a breeder, but for shelters and rescues, neutering is the norm.

If you’re interested in the specific results for each of the 35 breeds they examined data for, you can find it at the end of the study here.

Lori Ennis
Lori Ennis

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