Research also revealed an increased likelihood of other diseases linked to the spaying and neutering of the breed. The study, published in the online peer-reviewed journal PLOS ONE, looked at the rates of hip dysplasia, cranial cruciate ligament tears, lymphosarcoma, hemangiosarcoma and mast cell tumors in 759 Golden Retrievers examined during the past decade at UC Davis’ William R. Pritchard Veterinary Medical Teaching Hospital.
For all five diseases analyzed, the rates were significantly higher in neutered males and females, compared with intact dogs.
“The study results indicate that dog owners and service-dog trainers should carefully consider when to have their male or female dogs neutered,” says lead investigator Benjamin Hart, DVM, Ph.D., Dipl. ACVB.
“It is important to remember, however, that because different dog breeds have different vulnerabilities to various diseases, the effects of early and late neutering also may vary from breed to breed,” added Dr. Hart, a distinguished professor emeritus in the UC Davis School of Veterinary Medicine.
Early neutering, meaning before age 1, was associated with an increase in the occurrence of hip dysplasia and lymphosarcoma in males and of cranial cruciate ligament tears in both males and females. Late neutering — at 12 months of age or older — was associated with the subsequent occurrence of mast cell tumors and hemangiosarcoma in females.
The removal of a male dog’s testes (neutering) and a female’s ovaries (spaying) interrupts the production of hormones that play key roles in the closure of bone growth plates and the regulation of a female dog’s estrus cycle. Neutered dogs also tend to gain excess weight, putting pressure on their joints.
Previous studies have documented adverse health effects in neutered dogs of certain breeds. Those studies examined individual diseases using data drawn from one breed or pooled from several breeds, Hart says.
The UC Davis study drew its data from a single hospital database, distinguished between males and females, and between early or late neutering and non-neutering.
The researchers focused on the Golden Retriever because the breed is one of the most popular in the United States and is vulnerable to various cancers and joint disorders. The breed also is favored for work as a service dog.
Spaying or neutering is common in the United States before age 1 as a means of controlling both the dog population and unwanted behaviors. About 78 percent of dogs are sterilized, according to the American Pet Products Association.
The American Veterinary Medical Association supports the spaying and neutering of dogs and cats as a population control.
“Just as for other veterinary medical and surgical procedures, veterinarians should use their best medical judgment in deciding at what age spay/neuter should be performed on individual animals,” the AVMA policy states.
The doubling of the hip dysplasia rate among early neutered male golden retrievers surprised the researchers. Other studies had reported a 17 percent increase among all neutered dogs.
“Specifically for Golden Retrievers, neutering males well beyond puberty should avoid the problems of increased rates of occurrence of [hip dysplasia],” the researchers wrote in their journal article.
To read the full study, click here.
While the UC Davis survey has concluded, Morris Animal Foundation’s Golden Retriever Lifetime Study is just getting under way. The Denver-based foundation hopes to enroll 3,000 Golden Retrievers as part of a project that will track the dogs’ health and environment over their entire lives.
Owners may register their dogs at caninelifetimehealth.org.