Routine spaying and neutering of dogs is generally accepted, and some doggy daycares and dog parks don’t allow intact male dogs or female dogs in heat. In addition, many states require dogs in rescue shelters to be spayed or neutered before they’re placed in a home, often at just a few months old. Along with reducing pet overpopulation, spaying or neutering helps prevent unwanted litters that result in millions of dogs and cats being euthanized each year in the United States.
Nevertheless, a growing body of research suggests that spaying and neutering dogs, especially young dogs of large or giant breeds, can increase their chances of developing serious health conditions. Before going ahead with this procedure, make sure to consult with your veterinarian about the appropriate timing and the potential risks and benefits of spay-neuter.
What is Spay-Neuter?
Spay-neuter refers to the veterinary surgical practice of removing a dog’s reproductive organs, called the gonads. An exception to this practice is breeders who elect to keep their dogs intact for breeding purposes. Three common sterilization procedures are:
- Ovariohysterectomy (the typical spay) is the removal of the ovaries, fallopian tubes, and uterus, resulting in the dog being unable to reproduce
- Ovariectomy involves removing the ovaries while leaving the uterus intact
- Orchiectomy (the typical neuter) is the removal of the testicles, which makes the dog unable to reproduce, eliminates the main source of reproductive hormones, and may reduce or eliminate male breeding behaviors
What Are the Benefits and Risks of Spay-Neuter?
“When it comes to dogs, there is no one-size-fits-all recommendation,” says Dr. Jerry Klein, DVM, Chief Veterinary Officer for the American Kennel Club. The veterinarian will consider your dog’s age, breed, size, health status, sex, role (if they’re a pet or working dog), personality, and home environment in determining the optimal timing for this procedure. Generally, it seems better to delay surgery until the dog is more mature, he says.
For large and giant dog breeds, this could mean waiting until the dog is 12 months or older. In many cases, the benefits of spay-neuter outweigh the risks, he says. Still, it’s important to speak with your veterinarian about the benefits and risks of this procedure.
Benefits
- Reducing pet overpopulation and promoting a longer lifespan for dogs and cats
- Eliminating female dogs’ heat cycles and reducing mating-related behaviors, which can be frustrating to owners
- Reducing male dogs’ breeding instinct, resulting in less roaming and urine-marking behavior
- Preventing future possible reproductive tract diseases such as pyometra (a serious and potentially life-threatening infection of the uterus)
- Protecting male dogs by eliminating the risk of testicular cancer and reducing the risk of developing enlarged prostate glands (known as benign prostatic hyperplasia)
- Preventing and reducing the risk of breast cancer in female dogs
Risks
- Complications due to the surgery itself or being anesthetized
- Endocrine issues, especially in dogs with underlying health problems
- Greater chance of some types of cancers
- Increased risk of orthopedic disorders and soft tissue injuries
- Susceptible to urinary issues due to the presence or absence of hormones
Besides spay-neuter, other surgical options can prevent dogs from reproducing while keeping their hormone-producing gonads intact, Dr. Klein explains. These surgical sterilization methods, although used less frequently, aren’t expected to affect behaviors associated with the breeding instinct, he adds.
What Does Research Say About Health Outcomes?
A few decades ago, it became standard practice in veterinary medicine to neuter dogs at six months of age or even younger, in some cases. Since then, this practice has come under scrutiny with emerging research on the resulting health outcomes, Dr. Klein says. These include a higher risk of joint disorders (e.g., hip dysplasia), urinary incontinence, and some forms of cancer, according to a 2021 article.
One of the report’s lead authors, Dr. Benjamin Hart of the University of California, Davis, has been researching the effects of spay-neuter with support from the AKC Canine Health Foundation for a decade. His team found that early spaying and neutering is associated with an increased risk of joint disorders among large breed dogs, such as Golden Retrievers, Labrador Retrievers, and German Shepherd Dogs. More recently, these researchers conducted a retrospective study, investigating tens of thousands of dogs from 35 breeds, focusing on early spay-neuter before the dog reached sexual maturity. They found that the health consequences of the procedure varied widely between breeds.
“It’s hard to predict which ones will and won’t have an increase in cancers or joint disorders with early spay-neuter,” Dr. Hart says. For instance, in almost all dogs weighing less than 20 kilograms (about 45 pounds), there was no increased incidence of joint problems and cancers compared to intact dogs. One exception is the Shih Tzu. Early neutering of male Shih Tzu was associated with higher rates of some cancers.
The team found that, for dogs weighing more than 20 kilograms, the impact of early spay-neuter varies considerably across breeds and sexes. While small dogs didn’t experience higher rates of cancers and joint problems, Dr. Hart predicted that dogs at the other end of the scale, like Great Danes, might suffer these effects at a higher rate. An unexpected result was that these gentle giants had no increase in joint disorders after early spay-neuter.
Moreover, negative outcomes from spay-neuter were often limited to dogs neutered before they had reached sexual maturity. However, this isn’t always the case. For instance, female Golden Retrievers spayed after 12 months of age were four times as likely to develop hemangiosarcoma (an invasive cancer that causes damage to blood vessels) as intact females and even early spayed ones. Accordingly, more research is needed to understand breed-specific risks and benefits of spay-neuter.
How Have Views Evolved on the Timing of Spay-Neuter?
For a long time, many people believed that spaying or neutering a dog could prevent behavioral problems, as well as prostate and mammary cancers. Dr. Hart’s research revealed that neutering male dogs with aggression problems only resolved aggression in 25 to 30 percent of cases. In other words, three out of four dogs didn’t show an improvement in aggressive behavior after neutering alone. Significantly, those behavioral improvements were equally likely if a dog was neutered once they reached sexual maturity.
Based on available data, neutering doesn’t prevent prostate cancer. “As a matter of fact, prostate cancer in males is more common in neutered than intact dogs,” Dr. Hart says.
Existing studies on the incidence of mammary cancer are less conclusive, but research is ongoing through the AKC Canine Health Foundation and other institutions, so further guidance on decision-making is on its way. Meanwhile, Dr. Hart points out that both prostate and mammary cancer are relatively uncommon in dogs, whether they’re intact or neutered/spayed. Although testicular cancer is more common in older intact male dogs, it has better treatment outcomes compared to other cancers.
What Do Experts Advise Today?
“The take-home message is that it depends on a lot of different factors,” says Dr. Sharon Albright, Manager of Communications and Veterinary Outreach at the AKC Canine Health Foundation. These include the breed, sex, any major health concerns, and what the owner intends to do with the dog. She recommends speaking to your veterinarian to reach a decision that takes into account recent research, as well as the dog’s expected lifestyle. For instance, owners of active dogs (e.g., jogging partners or dog sports champions) should be well aware of the risk of joint problems before making a decision on spay-neuter.
Dr. Hart agrees. “One of the things I emphasize is the need for a paradigm change with regard to veterinarian-client relationships,” he says. He and his team would like the question of whether and when to spay or neuter to be a true discussion point between the veterinarian and the client. Both parties need to have all the necessary information about the likely impacts on the dog in question.
Dr. Albright also stresses that it’s important to consider how serious, common, and treatable the possible health outcomes are on each side of the spay-neuter decision, while also weighing the health and well-being impacts of unwanted pregnancies.
Keep in mind Dr. Hart’s advice that, although the risk of developing certain cancers and joint disorders increases when certain breeds are spayed or neutered early, most dogs won’t develop these conditions. The emerging research gives us a picture of the likelihood of certain outcomes, but it can never fully predict what life will look like for your dog.
Like people, each dog is an individual with their own of health and lifestyle needs, Dr. Klein says. For decades, America’s dogs were treated with a blanket rule about their reproductive organs. Though more research on spay-neuter is needed, with the information already available, dog owners can start working with veterinarians to make better, more informed decisions about what’s best for these beloved family members.
The Takeaways
While they’re major surgical procedures, veterinarians commonly perform spay-neuter procedures as they pose a low risk to a dog’s health and are thought to contribute to the improvement of over population of pets. Early spay-neuter can increase the risk of joint disorders and certain cancers, but the likelihood of these outcomes depends on the dog’s breed and age, as well as other factors. You should reach a decision about whether to spay-neuter and the appropriate timing through an informed discussion with a veterinarian about the risks and benefits of the procedure.