Over the past 50 years or so, veterinarians have recommended that dogs be spayed or castrated at about six months of age. At this age, female dogs would be spayed before their first heat, and male dogs castrated before reaching sexual maturity. When a female dog is spayed, the uterus and ovaries are surgically removed; when male dogs are castrated, the testicles are removed.
It is thought that early gonadectomy (spay and castration surgeries) helps prevent mammary tumors and uterine infections in females and reduces aggression in males, and, in fact, this is the case. Also, it has a significant benefit in controlling overpopulation. Between 10 and 20 million unwanted dogs and cats are euthanized at shelters each year in the United States.
The potential negatives of early gonadectomy are the tendency toward obesity, which can be managed by dietary changes, and the possibility for urinary incontinence in females, which can be managed with medication.
An increased risk?
A recent study at the University of California Veterinary School supports a growing body of evidence that early gonadectomy may also increase the risk for certain joint diseases and certain cancers in golden retrievers.
Recommendations for the age of spaying and castration of dogs in Europe are different from our country, and European veterinarians do not routinely recommend that dogs be spayed and castrated.
The study at the University of California was initiated to see whether the early removal of hormones that occurs with spay and castration surgeries (ovarian hormones in females and testicular hormones in males) has an effect on a dog’s propensity for certain diseases. In other words, do dogs (golden retrievers) in the United States, spayed or castrated at less than one year of age, encounter certain diseases that European golden retrievers who are not spayed or castrated (or spayed and castrated later in life) do not encounter or encounter less frequently?
A focus on golden retrievers
The study evaluated 759 dogs. Golden retrievers were selected because they are the most popular breed both here and in Europe, and also because they are prone to certain cancers and joint diseases.
In the study, dogs were divided into two categories: those operated on at less than a year of age and those operated on after a year of age or not at all. Cancers and joint diseases were evaluated because the removal of sex hormones can impact growth and normal organ function.
The following diseases were evaluated:
- Hip dysplasia (an abnormally shallow hip socket)
- Ruptured anterior cruciate ligaments (a ligament in the knee that tears)
- Lymphosarcoma (cancer of the lymph nodes)
- Hemangiosarcoma (cancer of the spleen)
- Mast cell tumors (aggressive tumors usually involving the skin)
Investigators found that all five diseases were affected by the age at gonadectomy.
- The rate of hip dysplasia doubled from 5 percent to 10 percent in animals spayed at a young age.
- No anterior cruciate ligament tears occurred in intact dogs compared to a rate of 5-8 percent in dogs operated on before one year of age.
- Ten percent of castrated male dogs developed lymphosarcoma—three times more than intact males.
- Hemangiosarcoma was four times greater in intact dogs—a plus for early surgery.
- No intact female dogs developed mast cell tumors.
Appropriate timing no longer straightforward
So what does all this mean? I think for golden retriever puppies, it is safe to say that the age at which a dog undergoes spay surgery or castration surgery is no longer straightforward. Simply recommending that a golden retriever pup be operated on at 6 months of age is debatable because the study showed that the age at surgery definitely could impact a dog’s health.
Also, it is important to realize that the study was performed only on golden retrievers, and that different breeds have their own individual tendencies to other diseases, and the effects of early gonadectomy may vary. Each pet is different, and your veterinarian will discuss the risks and benefits of when to spay or castrate your puppy.
East Bare Hill Road resident Fred Karotkin is a veterinarian.
