One of the most common questions pet owners have is at what age should they spay or neuter their new puppy. Traditionally, it has been recommended to sterilize dogs at puberty, around six months of age. This medical advice is based on facts. It helps control overpopulation of dogs and prevents massive euthanasia in animal shelters. In addition, it greatly decreases the risk of developing mammary cancer. Early neutering also prevents undesirable sexual behavior in dogs related to increased sex hormones.
More recently, this position has been challenged by scientific research. In the past, limited research on specific breeds revealed that some breeds have a higher potential to develop certain types of cancers and joint disorders when operated on in the first year of life. The findings were limited by the small number of breeds studied, and so no generalizations could be made. Research published by the University of California, Davis recently (July 2020) sheds light on recommendations for a broader number of breeds. The scientists evaluated the effects of early neutering and spay in 35 breeds. Their findings were very interesting: most breeds examined had no long term health risks at all, while others had a higher potential to develop specific types of cancers and joint disorders (specifically elbow/hip dysplasia and cranial cruciate ligament problems were studied). Some other breeds showed greater potential for long term health risks from the surgery for males than females. These findings demonstrate that a generalized cookie-cutter recommendation for an ideal time for spaying or neutering cannot be formulated.
This study also revealed that the size of a particular breed was a greater contributing factor to the risk of future joint problems than the age at which the breed is neutered. Bigger breeds (excluding Great Danes and Irish wolfhounds) have a higher risk of joint problems as compared to smaller breeds. This was also found to be true for certain types of cancers, with larger breeds being more at risk than smaller ones regardless of when they were neutered or spay. Two exceptions are Boston terriers and Shih tzus. It was found that these two breeds were more prone to cancer as a result of being neutered or spay, regardless of the age at which the surgery was performed. Gender was also found to play a role: male Boston Terriers have a higher potential for cancer when neutered early, as compared to female Boston Terriers. Golden Retrievers were found to have a greater increased risk of some cancers (5-15%) after neutering or spaying regardless of age.
In a nutshell, the decision of when to spay or neuter your dog should be carefully discussed with a veterinarian. Animal overpopulation is a real problem. Other possible influencing factors should be also explored, such as the role that puppy mills and the stores they supply play. We all want what is best for our dogs. We must consider their individual needs and discuss them with a veterinarian when deciding the ideal time to spay or castrate them.