Experienced Veterinarians Discuss When and If to Neuter or Spay Canines

The decision if and when to spay or neuter a dog is a personal decision that the owner must make, say three veteran veterinarians. They represent a total of 72 years of experience.

Their approach represents a significant change from decades ago when many veterinarians recommended altering (spaying or neutering) a pet puppy at six months to reduce the unwanted canine population.

Spaying means surgical removal of the female’s reproductive organs (the uterus and ovaries) and neutering is the surgical removal of both testicles, explains Richard Gastellum, DVM, of At Home Pet Dr. LLC. He’s been a small animal vet for 36 years, treating primarily pet dogs and cats, and offers a mobile service and in-office appointments in Buena Vista, CO.

During his vet training years of 1982-86, the emphasis was on canine population control, he says. He recalls being taught “There is no disease or condition of companion animals that take more of their lives than euthanasia.” At that time, he says that four to ten million canines were estimated to have been euthanized each year, many because of too many shelter dogs and not enough homes for them.

Times have changed. Julie Oghigian, DVM, CVA (certified veterinary acupuncturist) and the principal of Alpenglow Veterinary Hospital in Bozeman, MT, thinks since she started practicing 22 years ago that her clients are becoming more and more educated and many are aware of studies conducted about early altering at the University of California, Davis, (UC Davis) School of Veterinary Medicine. Her clientele includes many hunting dogs and canines that are either bred or shown in conformation and performance events. Some are pets.

Holly Tuttle, DVM, CVA, who has practiced for the past 14 years in the Metro Phoenix area, says about half her clients’ dogs are shown in conformation and/or performance events or are bred. The other half are pets that have come from rescues or shelters and have already been spayed or neutered. She has a strong interest in preventative care, behavior, reproduction, and alternative medicine including acupuncture. Many of her clients at Kennel Care Veterinary Hospital in Chandler also have heard about the UC Davis studies.

Both Oghigian and Tuttle breed and show their Labrador Retrievers. Gastellum hikes with his wife and their rescue dogs: a collie, a chihuahua, and two mixed breeds.

He says “each patient must be evaluated on an individual basis. There are so many factors that go into this decision and one size doesn’t fit all.”  That’s why he asks owners about their home life. Are there children living at home and other pets in the household, do they live in an apartment or home with a fenced-in yard so the canine can’t escape and other dogs can’t jump into the yard? Will the dog compete in performance events, hike, or stay at home as a pet?

Gastellum adds that the lifestyle of the owners and what they do, play a key role in the decision whether to alter.

He says the pros of altering include:

• the prevention of unplanned/unwanted pregnancy that helps control the canine population
• prevention of cancers related to reproductive organs including ovarian, uterine, and testicular cancer; and lessening the chances of developing mammary cancer (females)
• prevention or lessening undesirable behavior such as aggression and urine marking in males
• elimination of messy heats and attraction of unwanted male dogs

But, he adds, canine owners need to consider the negatives of altering:

• increased incidence of orthopedic issues, primarily cranial cruciate ligament rupture (CCL) and hip and elbow dysplasia
• possible increased risks of cancers including hemangiosarcoma, lymphosarcoma, mast cell tumors, prostatic adenocarcinoma, and transitional cell carcinoma of the bladder. This varies by breed (and sometimes by sex) and is much more important in the larger and giant breeds as well as for Boston Terriers and Shih Tzus.
• vulvar hypoplasia (tucked vulva) in females spayed at an early age
• possibly cognitive dysfunction

Oghigian, who has a strong interest in reproduction and canine sports rehabilitation, says the majority of pet owners want their females spayed because heats are messy and they don’t want any male dogs in the neighborhood howling outside their homes. She notes these owners also worry about mammary cancer and ovarian tumors which can reach baseball size if not spayed, and pyometra (infection of the uterus). Altering may be a convenience that allows owners to board their pets, she explains, because many boarding kennels will not accept intact dogs. Owners also may want to alter their canines because of aggressive behaviors.

When a client raises the possibility of altering, Oghigian discusses the pros and cons of spaying or neutering, taking into consideration the UC Davis research. If the owner’s reason for neutering is that the dog is marking his territory by piddling, she suggests training first.  She recommends not altering early if the dog will compete in performance events because the maturation of muscles, tendons, and a lean body are really beneficial, especially she says for agility.

“Hormonal maturation is huge,” she says. Early spaying forces early menopause which can weaken bones and tissues. She has noticed that “dogs neutered or spayed early tend to have slighter heads and bodies that look weedy-looking.”

While owners may be concerned about mammary cancers if their female dog is left intact, she says studies show such cancer is 50% benign, and keeping the female intact only minutely increases the chance of mammary cancer, says Oghigian. Numbers of mammary tumors double after that first heat cycle, but even doubled it is a very, very low percentage,  she adds.

In males, she says, testosterone really affects growth plates. If neutered before growth plates are closed, the bones will grow longer, thus making the dog look lankier and that affects the angles of joints, especially the cruciate and may cause susceptibility for tears later. Dogs have many growth plates which close at different times, she says.

She has many clients who keep their dogs intact and she’s had no problem with her two male Labradors who aren’t altered. One is now 13 years old!

Tuttle brings up the subject of neutering with clients when she first meets their new puppy. She asks them if they plan to alter their canine and discusses the pros and cons with them. By starting the conversation at this first meeting, her clients have time to consider and ask questions about altering their dog over the next several weeks when they bring in their ward for puppy shots.

If the owner isn’t going to compete with their dog in performance events and doesn’t want to breed, she discusses the health benefits of waiting to spay or neuter, and the dog’s purpose.

Gastellum says when his clients broach the subject of altering their canine, he discusses the pros and cons of doing so with them.

All three veterinarians consider the UC Davis research when advising clients on the benefits and negatives of altering their canines. If a particular breed wasn’t studied, they look to find the most comparable breed that was studied.

UC Davis Studies

Breeders of Golden Retrievers and Labrador Retrievers took note of a 2014 study by UC Davis that compared the long-term health effects of altering both sexes of those breeds at different ages. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0102241

The UC Davis comparison study showed that altering male and female Goldens at less than six months of age “ increased the incidence of  a joint disorder [hip dysplasia, elbow dysplasia, or cranial cruciate ligament(CCL) tears], 4-5 times that of intact dogs.” Altering Labrador males and females before six months of age doubled the incidence of one of the above three listed joint disorders.

Researchers found that neutering male Goldens between six months to eleven months of age showed a significantly higher incidence rate for hip dysplasia and CCL as compared to intact males. While the rate for CCL was significantly higher for spayed Golden females in that age range, there was not a significantly higher increase in elbow and hip dysplasia as compared to intact females.

In Labradors, the researchers found neutering before six months significantly increased the risk of males under a year developing elbow dysplasia or CCL, but not hip dysplasia. Spaying females before a year significantly increased the risk of hip dysplasia but not elbow dysplasia. Early altering of both sexes slightly increased the diagnosis of CCL.

Researchers also studied the effect of altering both breeds and sexes on cancers- lymphosarcoma, hemangiosarcoma, mast cell tumor, and mammary cancer. They found that spaying female Goldens increased the rate of those cancers by 3-4 times. Altering male Goldens and both sexes of Labradors slightly increased the occurrence of those cancers.

35 Breed  UC Davis Study

In 2020, UC Davis researchers studied canines representing 35 breeds for effects of associated joint disorders, cancers, and urinary incontinence if altered or left intact. https://www.frontiersin.org/articles/10.3389/fvets.2020.00388/full That same year they looked at the effects of early neutering of mixed breeds in five weight categories in connection with associated joint disorders and cancers.

The UC Davis researchers also found that “small-dog breeds seemed to have no increased risks of joint disorders associated with neutering and in only two small breeds (Boston Terrier and Shih Tzu) was there a significant increase in cancers.” Interestingly, researchers found that in two giant breeds- Great Danes and Irish Wolfhounds- there wasn’t an increase in joint disorders if altered at any age.

Researchers took into account the increased incidence of joint disorders and cancers when making recommendations for altering 35 breeds of dogs. For some breeds, they recommended to alter beyond six, twelve, and twenty-four months and in some cases, even those recommendations varied by sexes.

They suggested waiting until after six months

• to neuter male Cocker Spaniels, Corgis, and Labrador Retrievers
• to spay female Australian cattle dogs, Rottweilers, and Saint Bernards

The researchers recommended waiting until at least a year to

• neuter male Beagles, Border Collies, Boston Terriers, Golden Retrievers, Miniature Poodles, and Rottweilers
• spay female Border Collies, Collies, English Springer Spaniels, and Labradors

They advised that altering should be delayed until after twenty-four months for:

• male Bernese Mountain Dogs, Boxers, German Shepherds, Irish Wolfhounds, and Standard Poodles
• female Boxers, Cocker Spaniels, Doberman Pinchers, German Shepherds, Shetland Sheepdogs, and Shih Tzus.

Golden Retriever females and Doberman Pincher males should be left intact.

Mixed Breed Recommendations by UC Davis Researchers

For mixed breeds, the researchers urged veterinarians to consider the size of the dog when deciding on an age to alter. They broke sizes into five weight categories: small (˂22 lbs.), medium (22-42 lbs.), standard (43-64 lbs.), large (65-86 lbs.), and giant, 87 lbs. plus.

They found that dogs weighing more than 20 pounds “were significant risk for joint disorders” with altering but not so for dogs 20 pounds or less. Thus, they recommended waiting until beyond eleven months to neuter standard and large male dogs and to spay standard, large, and giant mixed females. Giant males, they noted, should be altered after 23 months of age.

“There was no clear picture with the cancers followed, undoubtedly reflecting the diversity of breeds involved in mixed breed dogs and the breed-specific differences with regard to vulnerability to different cancers.” See: https://www.frontiersin.org/articles/10.3389/fvets.2020.00472/full

Three vet recommendations/considerations

Gastellum says he considers the predominant breed in mixed breeds before recommending when to alter. He encourages owners to get their dogs genetically tested to assist in this decision. When mixed-breed combinations are unknown, he encourages neutering or spaying “only after sexual maturity if possible.”

He also takes into consideration a dog’s hormones and growth plates and is most concerned that long growth plates (tibia, fibula, femur, radius, ulna, humerus, pelvic, and vertebral) are closed. For most breeds, he tells clients that small and medium dogs’ growth plates close by a year, 14 months for large breeds, and 18-20 months for giant breeds.

Generally, Oghigian says she recommends waiting until a year old before altering a medium or large-sized dog and ideally after a female has completed her first heat as her extra hormones are in flux and to avoid recessed vulvas which can cause urinary tract infections and vaginitis issues. For small breed pets, she recommends waiting until six months to a year of age and for giant breed pets until two years of age.

When evaluating whether to spay or neuter, she takes into consideration a dog’s breed or a mix, say a doodle- the breeds comprising a doodle. For example, if the dog is a mix of a Golden Retriever and Standard Poodle, she’ll consider the UC Davis studies’ recommendations for both breeds.

She won’t hesitate to alter at an older age if there are other health risks involved.

Generally, Tuttle’s hospital’s policy is not to neuter small dogs under six months and large and giant dogs until at least a year. If the owner decides to wait, she asks them to call her if the dog develops aggressive behaviors.

Tuttle doesn’t find it easier to spay a younger dog than one older. She says if a dog is spayed early, there is more of a risk of an incidence of urinary incontinence. The recovery time for spaying is slightly longer than for neutering, she adds.

Gastellum dislikes spaying medium, large, or giant breed dogs that are six years or older because he considers them high-risk surgeries.  He says if the females have undergone multiple heat cycles, “the vasculature of the supporting uterine ligaments is dramatically increased and the uterine tissue is more friable (delicate to handle) and thus will tear and bleed more easily.”

He adds “Generally, their body condition is also increased.  Nothing is worse than spaying an overweight dog!”

“Older age dogs are also likely to have other complicating issues (heart, kidney, dental) and thus are at a higher anesthetic risk. They may even have joint issues such as arthritis necessitating great care in how they are positioned on the surgery table. They’ll need a more in-depth workup prior to surgery including blood/urine analysis. And, they will definitely be more expensive to do and their recovery will be longer,” he notes.

While in the past he has altered shelter dogs, Gastellum knows some are done as young as eight to twelve weeks and “in good conscious, I just cannot be a part of that anymore. While these surgeries on young and immature dogs are actually fun, quick, and easy, my good conscience nags me that I have probably set them up for orthopedic problems or cancers down the road. I prefer to be a bit more discretionary in my decision-making process when to spay or neuter. One size does not fit all.”

Gastellum also says that other surgical options exist in addition to the traditional spay or neuter but these procedures also have their pros and cons. Some vets only remove the female canine’s uterus and cervix but not the ovaries, which contains the primary source of estrogen. In males, vets may only do a vasectomy, sparing the testicles and thus preserving the beneficial effects of the hormone testosterone. Such procedures result in the canines’ inability to reproduce and “allows these pets to retain the much-needed benefits of these hormones.”

Will these procedures become more popular? Just last week Gastellum says he had a client with two male dogs who opted for vasectomy over traditional neutering.  Undoubtedly alternative procedures will become more popular as clients become more informed.  But, he adds, the conundrum for owners will be finding veterinarians who are willing and properly trained  to do these procedures.