Spaying Female Dogs: Facts and Fiction

It’s true that spaying can lower female dogs’ risk of developing devastating diseases such as pyometra and mammary cancer.

Female dogs don’t get automatically obese as a result of spaying. By: JACLOU-DL

Don’t you just hate lazy excuses?

One of my personal pet peeves are the people with grossly obese dogs who make the excuse “She was fine before she was spayed.”

They imply that neutering makes weight gain an irresistible steamroller of a force against which they have no control.

Weight Gain

Desexing slows the metabolism by a maximum of 5% — no more.

In practical terms, to keep a pet slim, at the time of neutering, switch from puppy to adult food (if they haven’t already transitioned), or cut portion size down by a small amount.

Obesity happens because the pet eats too many calories for the amount of exercise they get. OK, so you need to put in a tad more effort once the female is spayed, but it’s not difficult.

However, some people seem to think that desexing automatically means a chubby dog. Wrong!

Actually, sorting facts from fiction when it comes to neutering is more interesting than you might suppose. It’s relevant to everyone deciding on whether to neuter their female dog or not so they can make an informed decision.

But first, let’s recap a major reason for spaying female dogs.

Desexing: Ground Zero

Desexing dogs is important because it prevents them from breeding. Each year, rescue shelters euthanize millions of stray, neglected or unwanted canines.

The intact male dog who escapes has the potential to father countless unplanned puppies. So it isn’t just the spaying of female dogs that’s important but rather doctoring both genders.

Spaying helps keep the pet population from needlessly ballooning. By: Pixabay

Life Expectancy

OK, the good news is that desexed pets live longer than entire ones. This is a statistical fact.

The explanation for this is often a combination of factors, such as:

  • Desexed pets are less likely to roam and get into accidents or fights.
  • Desexed pets appear to get fewer life-threatening infections.
  • People who choose to desex their pets are usually thoughtful people who take their pets’ health seriously.
  • The rates of certain cancers (such as mammary cancer) or life-threatening conditions (such as pyometra) are higher in entire dogs.

Keep a longer life expectancy in mind as you read on. Remember, there are increased risks of certain conditions in spayed dogs; this rise is statistically small, especially balanced against a 1-in-4 chance of mammary cancer.

The Benefits to Female Dogs

Spaying a female dog most commonly involves removing both her uterus and ovaries (although ovarectomy, while leaving the womb in place, is becoming more popular).

At a stroke, this makes uterine cancer and ovarian cancer an impossibility.

The major advantage of removing the womb is that it prevents pyometra. This condition happens when the womb lining becomes infected and fills with pus. The infection then tracks into the bloodstream, making the dog toxic. Untreated, this leads to septicemia, kidney failure and death.

Yes, a pyometra can be surgically removed, but the surgery takes place on a sick dog and therefore the risks are greater. However, removing the womb from a healthy young dog places her at considerably lower risk of complications.

So do you take that risk now or postpone it until the dog is elderly?

If you aren’t going to breed from your female dog, then getting her spayed before her second season also protects her against mammary cancer. The latter is common in older dogs, with around 1 in 4 developing a mammary tumor.

So again, acting early could save her from surgery in later life.

Spaying after a dog’s second season is generally a good idea. By: JACLOU-DL

The Disadvantages to Female Dogs

There’s no doubt about it: Some spayed dogs are more likely to develop weaker bladder control in later life, while some are more prone to cystitis.

A typical story is the older female dog who wets her bed when deeply asleep. This is due to reduced tone in the valve exiting the bladder. However, this can be corrected with medication.

Balancing the arguments, there is a reduced risk of mammary cancer but a raised incidence of urinary incontinence. However, whereas cancer requires extensive surgery and can be life-threatening, incontinence can be managed with a simple daily pill.

The Downside of (Early) Spaying

Making an informed decision about desexing means knowing all the facts.

One of the benefits of the internet is that there’s more information out there for everyone — vets included! Analysis of research papers gives us access to statistics that were previously buried in libraries or university departments.

Looking at that data, it now looks like neutering does have a downside for some dogs, but let’s not get carried away here.

These increased risks are small and are for problems that already occur. So if an individual dog gets bone cancer, it’s difficult to know if they would have developed it anyway or whether there was a straight-line connection between desexing and the cancer.

It’s not a case of “Bone cancer never happens in intact dogs.” See the difference?

Listen to why this vet thinks spaying is a great idea for pets:

Those conditions with a slightly increased incidence in neutered dogs as opposed to entire ones include:

  • Bone cancer
  • Cancer of the spleen
  • Bladder cancer
  • Mast cell tumors
  • Ruptured cruciate ligaments

But here’s a thing: Remember how life expectancy is increased by neutering? This is where things get really complicated because the average age of neutered dogs is higher than intact ones.

We also know that the older a pet gets, the higher their risk of cancer … so how does increased life expectancy change the odds?

This is a case of the more we know, the more questions we have.

But as a guide, the experts who study these things in great detail advise it’s best to go ahead with spaying a female dog, but let her have 1 season first. Go ahead with surgery before her second season.

Spaying reduces the risk of a common problem while slightly increasing the risk of less common ones.

To spay or not to spay? The choice is yours.



This pet health content was written by a veterinarian, Dr. Pippa Elliott, BVMS, MRCVS. It was last reviewed Aug. 31, 2018.

Dr. Pippa Elliott, BVMS, MRCVS

View posts by Dr. Pippa Elliott, BVMS, MRCVS
Dr. Pippa Elliott, BVMS, MRCVS, is a veterinarian with nearly 30 years of experience in companion animal practice. Dr. Elliott earned her Bachelor of Veterinary Medicine and Surgery from the University of Glasgow. She was also designated a Member of the Royal College of Veterinary Surgeons. Married with 2 grown-up kids, Dr. Elliott has a naughty puggle called Poggle, 3 cats and a bearded dragon.

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