Veterinarians no longer use the blanket recommendation that you spay or neuter a dog after 6 months of age. Studies have proven that when you spay or neuter your dog can make a big difference in your dog’s future health.
Is There a Simple Answer to When to Spay or Neuter?
The recommendations cited in studies are not cut-and-dried, as you’ll see below. And a discussion with your veterinarian is always wise. We do have ballpark recommendations, but we urge you to read on to understand why:
- Small female dogs: 6 months of age
- Small male dogs: 6 to 9 months of age
- Large female dogs: After 12 months of age (you will have to endure one to two heat cycles)
- Large male dogs: After 12 to 18 months of age
The projected adult size of your dog makes a difference, as larger dogs tend to have big problems later in life if you spay or neuter too soon.
When you decide at what age to spay or neuter a dog, you’re weighing things like the likelihood of developing cancer, joint health, urinary incontinence in females, and excess prostate growth in males. Remember that aggression, behavior problems, and other issues may influence your choice, and that’s OK.
What Does Research Say About When to Spay or Neuter?
A 2020 study in Frontiers of Veterinary Science found the age at which we neuter our dogs—with neuter meaning surgically sterilize the dog so he or she cannot reproduce—can affect things like future joint health, the risk of developing cancer, and female urinary incontinence. They included 35 breeds in the study, looking at associated joint disorders, cancers, and urinary incontinence. “Guidelines that avoid increasing the risks of a dog acquiring these joint disorders or cancers are laid out for neutering ages on a breed-by-breed and sex basis,” the researchers wrote.
In 2024, Frontiers of Veterinary Medicine published a newer study that included German Short/Wirehaired Pointer, Mastiff, Newfoundland, Rhodesian Ridgeback, and Siberian Husky. The researchers again emphasized “the importance of personalized decisions regarding the neutering of dogs, considering the dog’s breed, sex, and context.”
An earlier study published in The Journal of the American Veterinary Association also found that the age of neutering or spaying may affect a dog’s joints—again for large dogs—saying, “In general, large- and giant-breed dogs were more likely than other dogs to have HD (hip dysplasia), CCLD (cranial cruciate ligament deficiency), or both” due to early neutering. Some veterinarians advise waiting until 24 months of age for giant-breed dogs.
And, of course, cancer risk in Golden Retrievers is a well-known concern, with a lifetime study funded by the Morris Animal Foundation. The chance of cancer in female Goldens is so high it makes the issue more should we spay rather than deciding what age to spay.
How Do Hormones Affect When to Spay or Neuter?
Whether your dog is male or female, the hormones testosterone and estrogen matter to your dog’s physical development and behavior. These hormones are made in the testicles or ovaries of a dog, so when the organs are removed, hormone production stops.
Consider that estrogen helps with muscle tone in the urethra, which is why some female dogs develop urinary incontinence. This is another good reason to delay a spay.
On the other hand, in a male dog, testosterone can cause abnormal prostate overgrowth in an intact male dog and impact rectal function. An enlarged prostate can block the path of feces through the rectum, which may result in emergency surgery. That’s a good reason to not wait too long to neuter your dog.
And, of course, if you have a canine athlete, these hormones affect muscle growth, drive, and performance in your dog. Owners of sporting dogs often postpone neuter or spay, especially with a large breed dog.
When Is the Best Time to Spay a Female Dog?
The decision on when to spay your female dog is not easy because there’s no answer that fits every dog. Discuss with your veterinarian what you want to do with the dog, your ability to handle a heat cycle (male dogs will seek her out and she will want to “meet” them!), and breed-specific concerns, like the Golden Retriever cancer risk. While vets don’t have crystal balls, they are familiar with the research on these issues and have a much wider base of experience than most dog owners.
In general, if you have a small female dog (under 40 lbs. projected adult weight), you have more leeway in choosing when to spay because smaller dogs seem less affected by all the orthopedic and cancer risks seen in larger dogs. If you want to avoid her having a heat cycle, many veterinarians will do a spay at 6 months of age as research shows no problem with this decision for most small dogs.
If you have a larger female dog, you need to weigh the developmental risks of an early spay against dealing with heat cycles. At about 1 year of age, skeletal growth is normally complete, making the lack of hormone production less likely to be a problem. However, that could mean you have to endure one or two heat cycles.
It’s important to know that the risk of mammary tumors increases in unspayed female dogs. That’s because intact female dogs have fully developed mammary tissue. A dog spayed prior to sexual maturity (around 6 months old) is at a reduced risk of mammary cancer because the spay removes the ovaries, which produce the estrogen that is significant to the full development of the mammary glands, according to Cornell DogWatch.
The Veterinary Society of Surgical Oncology (VSSO) says mammary tumors in female dogs account for 42% of all diagnosed tumors, with a lifetime risk of 23% to 34%. “Compare that to women, who have a 12.4% lifetime risk according to Susan G. Komen, an American breast cancer organization,” says Cornell DogWatch.
“At a cellular level, mammary tumors in dogs and cats are very similar to human breast cancer tumors,” says Dr. Scott Coonrod, the Judy Wilpon Professor of Cancer Biology and director of the Baker Institute for Animal Health. “And they may occur in pets even more often than they do in humans.”
When Is the Best Time to Neuter a Male Dog?
The decision on when to neuter your dog may depend upon what you’re going to do with the dog and your ability to handle an intact dog. Small-breed males are less affected by problems. With a big dog, your veterinarian may advise you to wait till 12 to 24 months of age to neuter your dog and ensure skeletal growth is finished. However, if you are having any temperament/aggression issues with your male dog, early neutering may be wise. Testosterone is linked to aggression. Consult a board-certified veterinary behaviorist for help.
How Much Does It Cost to Spay or Neuter Your Dog?
Not surprisingly, the cost of a spay or neuter is a regional thing. Prices in metropolitan areas can surpass $500 for a spay and $250 for neutering (castrating). If you’re working through a rescue or animal shelter, not only will they require that the dog is spayed or neutered, but they will often have low-cost plans to help control the births of unwanted puppies.
Leaving dogs intact and delaying spay/neuter is ruinous to dog overpopulation and the work of rescues. Far too many accidental litters result from delaying these surgeries.
It’s estimated that 334,000 dogs are euthanized in US shelters annually. It’s also estimated that if people stopped buying from breeders, the problem of dog overpopulation would cease to exist in only ONE to TWO years.
All breeds and mixes of dogs are dogs, domesticated creatures bred to depend on us for their survival. Publishing this article WITHOUT THIS CAVEAT shows not the love of dogs; it shows the interest of the selfish individual.
UC Davis vet school has a breed specific list of optimal times to stay and neutered. Female golden, as you mentioned, are recommended not to spay. That’s where other options, as Josie mentioned are helpful.
I what to keep my GSD female intact as long as possible. At what age should I spay to help avoid other diseases.
What about dwarf dogs, such as corgis (both breeds), bassets, dachshunds, etc.)?
Appreciate the information. Would like to see another article devoted to sterilization without desexing (similar to a tubal ligation for a female and a vasectomy for a male), the pros/cons, possible complications and trade offs.
Yes, I’d like to see that, too.
Yes, count me in on interest in such an article.