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Spay vs Neuter Your Pet: An Expert Guide to the Benefits and Challenges

Spay vs Neuter. In this expert guide, we discuss the differences as well as the risks and benefits of the pet procedures.

Image of puppy in vet clinic. Spay vs neuter pet should happen at an early age. Photo: basykes

Let’s get this out of the way: Spaying or neutering is the best thing for your dog or cat. Unfortunately, veterinarians who advise this still get a good bit of resistance from some people. Culture and ignorance dictate what people think when it comes to this issue.

In this guide to spaying or neutering your pet, we talk about the pros and cons, and provide some expert advice.

Here’s what we’ll cover below:

  • The difference between spay vs neuter
  • The many benefits of spaying or neutering your dog or cat
  • How old should your dog be when you spay or neuter?
  • Myths and facts about spaying and neutering dogs
  • Why spaying is not just a “simple snip”

Ready? OK! Keep reading, and you’ll arm yourself with lots of information in this vet-written expert guide.

Spaying or Neutering a Cat
Talk with your veterinarian about spaying or neutering your pet. Photo: Alexas_Fotos 

The Difference Between Spay vs Neuter

Spay vs Neuter: they are terms commonly used to describe the surgical sterilization procedures for pets, but they refer to different methods depending on the sex of the animal. Here’s a detailed look at the differences:

Spay / Spaying (Ovariohysterectomy)

Spaying, scientifically known as an ovariohysterectomy, is the surgical procedure performed on female animals. This surgery involves removing the ovaries and usually the uterus as well. It’s a more complex and invasive procedure compared to neutering because it involves entering the abdominal cavity.

Neuter / Neutering (Castration)

Neutering, or castration, is the surgical procedure used to sterilize male animals. This process involves the removal of the testicles, which inhibits the production of testosterone and the ability to impregnate a female.

Key Differences

  • Procedure Complexity: Spaying is generally more complex and may involve greater post-operative care due to the nature of entering the abdominal cavity. Neutering is less invasive, involving only small incisions in the scrotum or near the base of the penis.
  • Behavioral Impact: Both procedures help in curbing undesirable behaviors, but neutering has a more pronounced effect on aggression and roaming in males. Spaying eliminates heat cycles in females, which can be particularly bothersome in cats.
  • Health Benefits: Both procedures offer significant health benefits, but the benefits differ due to the different health risks faced by males and females.

Considerations for Timing

The timing of when to spay or neuter a pet can depend on various factors, including the type of pet, its breed, and its health condition. Generally, veterinarians recommend these procedures before the pet reaches sexual maturity to maximize health benefits, but the timing should always be discussed with a veterinarian.

Both spaying and neutering are crucial steps in responsible pet ownership, contributing to a happier, healthier life for pets and helping to control the pet population effectively.

Benefits of Spaying or Neutering Your Dog or Cat

One thing is certain: Cost should not be a factor.

If your regular vet has a fee that presents a hardship for you, there is plenty of assistance from many organizations and quite a few low-cost spay/neuter clinics around. Ask your vet or check out the Humane Society or the ASPCA.

If you’re considering adopting a pet, then know that many reputable shelters will not adopt without the animal being spayed or neutered. This includes puppies and kittens because of safe early spay/neuter programs.

And if you’re buying a pet?

Then you should be able to afford the spay/neuter.

Health Benefits

There are many health benefits to spaying or neutering:

  • Females are at less risk for infections of the reproductive tract (pyometra) and mammary tumors (breast cancer).
  • Males will not develop testicular tumors and will be less prone to prostate and associated urinary problems.

Cats, in particular, will have less exposure to fatal diseases such as feline leukemia and the feline AIDS virus if they are spayed or neutered. They will fight less and will not be mating, which means they will be avoiding the most common ways these feline diseases are spread.

Behavioral Benefits

Behavior problems are lessened when a dog or cat is spayed or neutered:

  • Males tend to exhibit fewer testosterone-driven behaviors, such as urine marking, aggression and roaming.
  • Females are less likely to fight as well.

Animal Welfare Benefits

Obviously, your pet will not be able to reproduce, which will help control the ever-growing and unwanted pet population.

Overpopulation in cats is even more extreme than in dogs. That’s why you should never let your cat “have kittens” just for the supposed cuteness factor.

The next few sections of this article talk specifically about dogs, but much of the following applies to cats as well.

Spaying or Neutering Your Pet
Talk with your vet about the best time to spay or neuter your pet based on breed, size and lifestyle. Photo: itsgreg

When Should You Spay or Neuter Your Dog?

When to spay or neuter your dog? And why? Vets grapple with these questions every day and invariably come to different conclusions.

To add to the struggle, we’re finding that new evidence is putting fresh wrinkles on this subject and making the “when” and “why” more of a controversial issue.

So, when should you spay or neuter your dog? Unfortunately, there is no right or wrong answer — but there sure is a lot of “chatter” out there. Let us explain …

Traditional Thought

For the past 30–40 years, the majority of vets have recommended spaying or neutering dogs at around 6 months old or soon after that. Here’s why:

  • There are indisputable health, behavioral and animal welfare benefits, which we mentioned above.
  • Spaying or neutering at around 6 months of age is a much easier surgery for your pet (and your pocketbook). Older spays/neuters are technically more difficult and cost more.
  • Older dogs who are not spayed or neutered and need advanced, expensive care may not get the care because their people can’t afford it. This means euthanasias for avoidable problems.

The 3 Camps of the Spay/Neuter Issue

  1. Rescue and animal welfare advocates say spay or neuter as soon as possible to avoid any chance of an unwanted litter, even if that means doing the surgery at 7–8 weeks old. They claim there is no evidence that this early spay/neuter causes any complications. Mildly controversial but still unknown.
  2. Responsible people suggest spaying or neutering puppies at an early age, 6–9 months. These dogs do not run the risk of developing health problems associated with not being spayed or neutered, and the surgery is easy on them. (We fall into this camp.)
  3. People or breeders who want to wait for unproven reasons. There is some evidence that large-breed dogs might benefit from a later spay/neuter. They may be less likely to develop orthopedic problems, such as an ACL rupture or certain cancers. More research is needed.

Our Take on When to Spay or Neuter

Talk honestly with your vet about the best time to spay or neuter your dog.

Breed, size and lifestyle should come into this discussion.

Don’t sign a breeder contract saying you won’t spay or neuter — once you buy the dog, they are your dog. We hope you won’t purchase at all — please adopt instead. Regardless, no breeder should tell you what you should do with your own dog.

Always consider that an intact dog is ready to make puppies. We don’t want to depress you with the numbers of dogs still killed in shelters because people didn’t spay or neuter … but the numbers are staggering.

Next, let’s talk about some facts and fiction when it comes to spaying or neutering. We think you’ll be fascinated by this part of the article …

Spaying or Neutering Your Pet
No, female dogs don’t automatically get obese as a result of spaying. Photo: JACLOU-DL

Spaying Female Dogs: Facts and Fiction

Don’t you just hate lazy excuses? Among our personal pet peeves are those people with obese dogs who make the excuse “She was fine before she was spayed.” They imply that spaying makes weight gain an irresistible steamroller of a force against which they have no control.

Will Spaying My Dog Make Her Fatter?

No, probably not. Desexing slows a dog’s metabolism by a maximum of 5% — no more.

In practical terms, to keep your dog 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 or not to spay their female dog so they can make an informed decision.

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

Life Expectancy of Spayed/Neutered Pets vs. Intact Pets

The good news: Spayed or neutered pets live longer than intact ones.

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 much 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 of Spaying Your Girl Dog

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).

This makes it impossible for the dog to get uterine cancer or ovarian cancer.

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 so the risks are greater. However, removing the womb from a healthy young dog places her at a much 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 your dog, then getting her spayed before her 2nd 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 female’s 2nd season is generally a good idea. Photo: JACLOU-DL

The Disadvantages of Spaying Your Girl Dog

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, we see 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:

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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 2nd season.

Spaying or Neutering Your Pet
Whether your male dog needs neutering depends on a variety of factors. Photo: Pixabay

Neutering Male Dogs: Fact vs. Fiction

What are the pros and cons of neutering male dogs?

It’s a question often asked about male puppies, especially when they reach that rambunctious, playful, bonk-their-favorite-cuddly-toy phase.

Indeed, some people react emotionally about making this decision. Many (often men) are dead-set against desexing surgery, while others assume surgery is mandatory without questioning the whys and wherefores.

Take the Middle Path

Taking the middle ground is closer to the ideal path, with people making an informed decision.

It’s important to consider each male dog as an individual, then weigh up what’s best for their health and their behavior.

The arguments for neutering male dogs aren’t as compelling as those for female dogs. That’s why it’s worth taking time to think through your reasons for going ahead with surgery — or not.

Don’t get us wrong — there’s definitely a place for neutering. But there are downsides, and for some males it’s actually the wrong thing to do.

So don’t jump to conclusions right now because some of the arguments below may surprise you …

Spaying or Neutering Your Pet
Neutering isn’t a cure-all for aggressive behavior. Photo: homar

Fact or Fiction?

All aggressive dogs should be castrated.


Are you surprised?

For genuinely aggressive dogs, then yes, castration is advisable. It reduces levels of circulating testosterone and helps smother the flames of aggression. However, surgery should not be looked on as a cure-all.

Equally as important is working with a certified behaviorist to address the dog’s underlying issues.

For a subset of aggressive dogs, neutering can make their behavior worse rather than better. These are those anxious dogs who lack self-confidence. They find the world such a big, scary place that they try to keep it at paw’s length by growling, snapping and biting.

Neutering a super-anxious dog removes the boost of confidence that testosterone gives them, thus heightening their anxiety.

If this sounds like your dog, then rather than rush ahead with surgery, discuss their behavior with a vet or a certified behaviorist to work out the best course of action.

Neutering stops dog humping.


If a mature male has an established humping habit, some of this is learned behavior rather than hormone driven.

Yes, neutering the dog may help, but there’s no guarantee. It could be a habit.

Many puppies who are the dog equivalent of toddlers (and not gone through puberty) get “excited” around toys or their litter mates. This humping is about experimentation and establishing pecking order rather than procreation, so neutering at a super-young age has limited benefit.

However, desexing males does have a role. Catch them in that sweet-spot when the behavior is sexual but before it becomes a habit, and the snip should do the trick.

Neutering your dog prevents testicular cancer.

Fact … with a “but” attached.

The testicles are removed during surgery, so yes, neutering prevents testicular cancer.

But testicular cancer tends to be slow-growing and non-malignant (it doesn’t spread). Should an intact dog develop testicular cancer, then prompt surgery should put things right.

However, statistics show us that neutering very slightly increases the risk of prostate cancer in dogs. The bad news is that this cancer is aggressive and responds poorly to treatment.

Please note that this increased risk is only slight — so don’t panic if your dog is already neutered.

Spaying or Neutering Your Pet
A male dog’s personality may change for the better once he’s neutered. Photo: Myriams_Fotos

Neutering prevents diseases linked to testosterone.


High testosterone levels over a long time can lead to an enlarged prostate gland (a condition known as benign prostatic hyperplasia) or anal adenomas (fleshy tumors that grow near the anus).

Removing the testicles and lowering testosterone levels drastically reduces the risk of these conditions developing.

Neutering increases the risk of some other cancers developing.


Again, the increase is very slim — so slim, in fact, that vets haven’t been certain until recently.

However, there is a small increased chance of developing osteosarcoma (cancer of the bone) or hemangiosarcoma (cancer of the spleen) in neutered male dogs.

This statistic is most relevant to large or giant dog breeds. The increased risk is less evident in smaller dogs to the point of not worrying about it.

When making your decision, be aware that the timing of surgery seems to play a role. A large-breed male dog who is physically mature and has stopped growing when neutered seems to buck the trend for an increased risk.

Neutering will change my dog’s character.

This is a tricky one: Yes and no.

Neutering does alter character, but usually for the best. If it has a noticeable effect, it’s usually to make the dog into his “better self,” with some of the naughty kinks ironed out.

What neutering doesn’t do is change the dog from an intelligent, playful pup into a characterless lump.

Neutering will change the dog’s coat.

Yes — this does sometimes happen.

For some dogs, neutering does change a smooth glossy coat into a fluffy, wavy one. It doesn’t happen to all dogs, but it does happen.

If you do decide to spay or neuter your pet, here are some helpful tips for post-surgery care:

Reminder: Don’t Forget This Super-Important Reason to Neuter

Population control!

Let’s not forget that animal shelters are overflowing with stray or unwanted dogs.

A male dog can detect a female in heat from miles away. One male dog who escapes and follows the call of nature could end up fathering dozens of unplanned puppies, with potentially heartbreaking consequences if those pups don’t have homes.

Also, male dogs running after a female in estrus are more likely to get hit by a car.

Yes, a big cause of death in intact dogs is their hormones making them overlook road safety.

Spay or Neuter My Dog
Spaying females has health benefits, but there’s no “simple snip” when it comes to spay surgery. Photo: Katie Brady

The Myth of the Simple Snip: The Truth About Spaying

Vets spay dogs and cats every day. Drop the dog off, have ‘er fixed and pick ‘er up.

Routine surgery. Right?

Well, maybe not.

The spay surgery can be fairly straightforward in trained hands, but it is nevertheless an open abdominal surgery. A dog spay is one of the more difficult surgeries general veterinarians perform.

Spays usually go well, but they are not “easy” by any means. Young vets learn a lot about surgery pretty quickly when they are unable to do their first dog spays without lots of assistance from a seasoned surgeon.

The veterinary community has encouraged people to spay and neuter their pets for decades because the majority of practicing vets are huge animal welfare nuts. We are also aware of the health benefits of spaying or neutering.

But in order to encourage most people to spay or neuter, many vets have made the surgery sound like a walk in the park. We don’t want to scare people away from having it done for their pets, so we minimize the complexity of the procedure.

Vets have also undercharged for spays for decades. If it doesn’t cost much, it must be really easy, right?


All Spays Are Not Equal

There is more surgical technique required for a spay, particularly a difficult spay, than many other surgeries performed in a general practice.

And what makes a spay “difficult?”

1. Age of the Dog

The structures in a young dog are smaller with smaller vessels. The difference between spaying a 6-month-old and an 8-year-old dog can be huge.

2. Body Condition

Obesity in pets may be one of the biggest nightmares when we approach a spay.

Think about opening up that 12-pound Dachshund and having 8 pounds of gelatinous fat pop out of the abdomen. A fat dog also has extra fat around the ovaries and uterus, complicating the procedure.

3. Multiple Litters or Heats

With every year that passes, heat cycles and/or litters can change the uterus, making it larger, bloodier or more friable (fragile.)

4. Breed

A German Shepherd surgery is not the same as one for a Maltese.

That being said, you never know what you’re going to find until you get in there.

Larger does not always mean more difficult. A deep-chested dog may actually be easier than a fat little Pug.

Remember, too, that our patients are under full anesthesia. So special care must be taken with tiny animals, brachycephalic breeds with respiratory issues, etc.

5. Health Status

Concurrent conditions such as heart or kidney disease, or diseases of the reproductive tract, obviously complicate a spay.

Follow the Post-Op Instructions

So, say the spay surgery went great. You go home with written and in-person discharge instructions, to leash walk only for a week, and use the Elizabethan collar if the dog is a chewer.

Follow the instructions. No — really follow them.

That means no Frisbee. The dog wears the collar as instructed so she doesn’t lick the incision.

Spays desire respect and diligence, both from you and the surgeon. Your dog may be bouncing about at home post-op, but she went through a major surgery, and you need to be her guardian.

Even if you yourself have felt OK after a surgery and your pain is managed, you know enough to be careful about your incision. Ms. Post-Op is hard-wired to show no weakness. She will leap and bound on that newly sutured abdominal wall unless you put a lid on it (and an E collar).

Final Thoughts on Spaying or Neutering Your Pet

All of this makes deciding whether or not to spay or neuter your pet a considered decision.

If in doubt, talk these issues through with your veterinarian. Then you can decide what’s best for your dog based on the dog’s individual risks and needs.


vet-cross60pThis pet health content was written by veterinarians, Dr. Debora Lichtenberg, VMD, and Dr. Pippa Elliott, BVMS, MRCVS. It was last updated Aug. 15, 2019.
If you have questions or concerns, call your vet, who is best equipped to ensure the health and well-being of your pet. This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. See additional information.