BY: Samantha Bartlett, DVM  

Researchers from University of California, Davis have published a 10-year study linking dog breed, sex and age with risks of certain cancers and joint disorders after early neutering or spaying.  The study was published July 7, 2020 in Frontiers in Veterinary Science. 

The study examined 35 dog breeds. Researchers found that there is a large disparity between breeds as to health risks and age at sterilization. The study was conducted using data from dogs examined at UC Davis Veterinary Medical Teaching Hospital over a 15-year time span. Joint disorders examined included hip dysplasia, cranial cruciate ligament tears and elbow dysplasia. Cancers included lymphoma, hemangiosarcoma, mast cell tumors and osteosarcoma. Researchers found that the risk of developing any of these conditions was not affected by age of neutering in most breeds. 

The risk of developing joint disorders was found to be more related to body size rather than age of sterilization. The majority of large breeds tended to have joint disorders where smaller breeds tended not to have problems in this area. The two giant breeds examined – great Danes and Irish wolfhounds – did not appear to have any increased risk of joint disorders when neutered at any age. Small breed dogs also appeared to have a lower risk of cancer occurrence whether sterilized or kept intact. The exceptions were the Boston terrier and shih tzu where researchers found significant increases in cancers with neutering. 

The authors acknowledge the study is limited by the number of records studied and the limited number of breeds. However, the overall conclusion is that age at neutering cannot be a blanket guideline. The study includes guidelines for each of the 35 breeds studied to assist pet owners and veterinarians on making a decision to spay or neuter. The full study and breed recommendations can be found at https://www.frontiersin.org/articles/10.3389/fvets.2020.00388/full