Why Spay or Neuter Your Dog or Cat? Here’s 5 Important Reasons

So you’ve got that new puppy or kitten and you’ve been agonizing over getting him or her “fixed” and when. Perhaps your breeder has told you one thing and your next door neighbor has told you another. It’s also possible you adopted a pet from a shelter or rescue (for which we’d like to say thank you!) and the decision to spay/neuter was already made for you but you’re interested in this topic all the same.

In this article, we’re not going to discuss in detail exactly when to spay or neuter. The recommendations can vary depending on whether your pet is a cat or dog, male or female. And for dogs, things can vary further based on a pup’s breed, her expected mature adult weight, and other circumstances. Because there can be several factors at play, this is a discussion best left for you to have with your own veterinarian.

But why neuter a dog or cat at all? Why spay?

You may think you know some of the reasons, or maybe you think of it as just “something you do” when you get a new pet. But there’s probably at least two or three reasons you’ll read about in the following article that you didn’t realize were important to consider. And there are many folks out there who don’t see a need or reason to spay or neuter at all. This article is for you too. If you decide not to spay or neuter your pet, it’s really important to make an informed decision and know the risks of not having this procedure done.

And yes, because cost, anesthesia, and the word “surgery” are concerning to almost everyone, we’ll talk about this as well.


Important Reasons to Spay or Neuter


Nature finds a way. And when a female dog goes into heat, her main goal is to find a male. Likewise, an intact male dog is always on the lookout for the ladies. In either case, they try to find a way to get to each other. Cats can be even more of a challenge, because they aren’t limited to 1-2 heat cycles a year. Cats are induced ovulators and can go into heat at any time if the conditions are right. If there’s a male tomcat that slinks around your house, your intact female kitty is likely to go into heat just because he’s around.

For both dogs and cats, this means that any measures you might normally take to keep your pet indoors or kept to the confines of your property are going to be under strain. A small weakness in the fence, forgetting to completely close the door, leaving the window slightly open, even a light adjustment on the leash can all be taken advantage of and it happens more often than you might think. Before you know it, your pet is off down the block, picking up scents no human being could ever appreciate.

Roaming might be the single most important reason to consider spaying or neutering from a pet’s safety standpoint. It’s also the least thought of. If your pup or kitty gets out, there’s no barrier he won’t cross to find that willing female, and vice versa. This includes busy streets with lots of traffic. It includes encountering other roaming dogs and cats and the risk of fights.

Roaming is also a common reason why pets simply get lost, can’t find their way home, or get picked up by local animal control. This is one of the most important reasons to have a pet microchipped. Very few pets without a microchip ever get returned to their owners. Sure, a rabies tag can be traced to a veterinary practice and a home address tag says it all, but these can often get lost or even more importantly, they can be intentionally removed.

Now fortunately, a dog can’t usually get pregnant on her first heat cycle, but she’ll still try and thus the danger of roaming behavior is still present that early. And don’t be fooled by some reports that dogs never go into heat until 12-14 months. This can happen as early as 6 months, with many dogs experiencing their first heat between 7 and 9 months.

As for cats? Well, lets just say that my own three cats, two boys and one girl, were showing signs of mating behavior at 5 months. This was also in December when cats, as traditionally held “long day breeders” or “spring/summer breeders” aren’t “supposed” to be interested in mating. It just goes to show that no prescribed pattern is ever guaranteed in nature.

But fortunately, within a couple of months of spaying or neutering and a large drop in circulating sex hormones, the urge to roam evaporates in most dogs. Cats can be a little different because they naturally prefer to roam, hunt, and seek out other cats, but it should still make a difference. According to a research team with the University of Illinois that tracked a group of 42 cats for a two year period, most indoor/outdoor cats with a home stay near their own property but still roam an average area of about 5 acres. This is far less than a square mile but still amounts to over 200,000 square feet. One feral cat they tracked roamed an area of about 2 square miles.

But you would think that without mating on the brain, a domestic cat would be far more likely to just stick to his territory to defend it, hunt what he finds in the backyard, and do little else.


Population Management: Reducing Disease

If you’ve ever been to a county animal shelter, chances are it looked pretty full. Depending on the state and the county, a shelter might be very well equipped and staffed to handle a large volume of stray animals, or it might not.

Many shelters in the United States are suffering from an inordinate volume of incoming dogs and cats and limited resources to handle them. Overflowing shelters lead to stressed and scared animals, disease outbreaks, and unfortunately, the euthanasia of many otherwise healthy potential pets.

There are a lot of rescue groups out there doing good work to get dogs and cats out of so-called “kill” shelters and into good homes, but they can’t save them all and the cycle is perpetual.

In the United States, we take things for granted. In Caribbean and Central American countries I’ve visited, dogs and cats largely roam free. A majority are malnourished, suffering from parasites and disease. And in addition to diseases suffered just by unfortunate stray animals, the health risk to people is quite high when a large population of animals around them is suffering from malnutrition, parasitism, and disease.

So while it may seem like a hard line to take, population control in our pet population is extremely important. And while there are other circumstances that contribute to this problem, like pet abandonment, spaying and neutering goes a long way to reducing the number of homeless pets



Cancer Prevention

It may sound overly simplistic to say that if reproductive organs are removed through spaying or neutering, that any risk of cancer associated with those organs is thus removed 100%, but it’s true. A dog can’t get testicular cancer if he no longer has the family jewels.

But what I often have a conversation with pet owners about has little to do with cancer of the reproductive organs themselves, like the ovaries and uterus. It’s breast cancer. Treating breast cancer in humans has made some leaps and bounds over the last decade, but breast cancer in dogs is still a bit of a gamble and a dog’s risk for developing it depends greatly on when she is spayed.

I saw two dogs, each diagnosed with mammary adenocarcinoma, follow very different paths. The first dog had a lumpectomy but passed away six months later from metastatic spread. Surgery wasn’t an affordable option for the second dog, but even with the same diagnosis, she was still trucking along a year later.

Mammary cancer in dogs is unpredictable. But even without metastatic spread, it can be ugly. They can develop large, firm, ulcerated masses that can be quite painful. And since dogs typically have 8-10 mammary glands, there are far more opportunities for masses to develop. Full mastectomies in humans are notoriously painful and involve a difficult recovery, but that’s only for one or two glands. Now consider having what’s called a chain mastectomy where all 8-10 glands on one side are removed. Then the other side has to be done several weeks later. This is often necessary in dogs if cancerous masses are spread out through several glands.

The great news is that if spaying a dog is timed right, the risk of developing mammary cancer is very nearly zero and all depends on the heat cycle.

If a dog is spayed before her first heat cycle, typically anywhere from 7-14 months, the ability to prevent mammary cancer is nearly 100%. If we do allow the first heat cycle to occur but spay a dog before her second (which typically doesn’t occur again for at least several months), the prevention rate drops into the 90s, but is still quite high. But after the third heat cycle, the prevention rate drops down near 50% and continues to drop.

Now, deciding when to spay, as I said earlier, is a conversation best had with your veterinarian. In some breeds, like Golden Retrievers and German Shepherds, there’s data showing that spaying later may be more beneficial for their skeletal growth and avoiding certain kinds of orthopedic disease later in life. I typically discuss balancing the risks and benefits for spaying and neutering and matching those with a pup parent’s goals. You need to have the same conversation with your vet to make the most informed decision.



The Dreaded Pyometra

Some folks may have heard of a pyometra while others may have not. Essentially, it is an infection of the uterus, which fills up with pus, and can only happen to a dog during the period shortly after she finishes a heat cycle. When a dog is in heat, white blood cells are blocked from entering the uterus so that sperm can have safe passage. After heat is over, progesterone kicks in and the uterine wall becomes thickened to prepare for pregnancy.

But if pregnancy doesn’t happen after several heat cycles, the uterine wall can continue to thicken and eventually can develop cystic structures. These cysts are the perfect environment for bacteria to grow, and a secondary infection develops.

A pyometra is a very dangerous condition and by itself is often discussed with pet owners as an important criterion for spaying. And with good reason. Some pyometras can be “open” meaning the infected material, usually fluid, can drain to the outside. But because one of progesterone’s jobs is to keep the cervix closed, this infected fluid more often has nowhere to go. The uterus then starts to fill up like a water balloon. And as we all know, over-filling a water balloon will eventually lead to it bursting open.

If a pyometra ruptures into the abdomen, which I have unfortunately seen happen, the spread of infection is often too great and severe for a dog to recover from.

A veterinarian will suspect a pyometra if a female dog, recently out of heat, presents with a high fever, decreased appetite, and lethargy. We can confirm the presence of a pyometra using x-rays and/or ultrasound.

But even if a pyometra is caught prior to it rupturing, the only way to treat a dog with this condition is to surgically remove the infected reproductive tract. Sometimes an open pyometra can be treated cautiously with antibiotics, but these often develop into closed pyometras and no pup with a closed pyometra will ever recover without surgery. And surgery as you can imagine, is risky. If the infected uterus leaks or breaks open before it can be fully removed from the abdomen, a pup’s chances of successful recovery are much lower.

So now you can understand why pyometras are so dangerous. A pet owner is given the choice between a risky, expensive surgery when their dog is already sick, or euthanasia, which is often the only other humane choice we can offer.



Those Crazy Hormones: Behavior

When I think about canine behavior when it comes to sex hormones, I can’t help but think about Cousin Eddie from National Lampoon’s Christmas Vacation. He laughingly tells Clark Griswold that his dog, affectionately named “Snots” (”you ain’t never seen a set on a dog like this one’s got, Clark”), that “if the mood catches him right, he’ll grab your leg and just go to town.”

Spaying and neutering can certainly help with some behaviors, including the leg-humping behavior Snots is fond of. It can also reduce to some degree a dog or cat’s territorial nature and may make him or her less wild and crazy. It does virtually eliminate a male tomcat’s territorial habit of urine spraying around your house.

But don’t have a high expectation that spaying or neutering is going to fix a majority of behavioral problems your pet may have. The only solution to most behavioral issues is appropriate training and conditioning at an early age. If you have an older dog that has come to you with some pre-existing behavioral concerns, ask your veterinarian for recommendations for good in-home trainers in your area, or seek the assistance of a veterinary behaviorist.



Okay, I Get the Benefits. But What About Cost? What About Anesthesia Risk?

In practice, I typically encounter four reasons why a pet owner is hesitant to spay or neuter their pet and I think it’s important to address them, because they may be the same reservations you have.

Cost Complications

The cost for a spay can vary, but is usually a couple hundred dollars, sometimes more. Neuters are much less. Why? A spay is an abdominal surgery while a neuter is not. So it certainly is something to plan for financially when you have a new puppy or kitten. But the good news is that there are likely a couple options available in your area.

Spay/neuter clinics are found commonly now, and their sole purpose is to provide a spay/neuter service with a licensed veterinarian at a reduced cost. It is important to note though, that spay/neuter clinics often do not provide pre-operative bloodwork, have very basic anesthesia monitoring (or sometimes none at all), and provide minimal aftercare. Your own veterinary clinic is likely to provide a higher care standard. This is a situation where you have to carefully weigh the risks vs. the benefits. Local rescue groups also may be able to help at least cover some of the cost of a spay or neuter surgery, especially if you adopt through them.

My final thought about cost is to consider how much a spay costs (a couple hundred to a few hundred dollars usually) in comparison to the cost of a pyometra surgery or mastectomy. These surgeries, often carrying a higher degree of difficulty to perform and a higher risk to the pet, are always much more expensive, usually costing at least a couple thousand dollars. From that perspective, spaying at an early age is a bargain.



Anesthesia Anxiety

The term anesthesia is very scary for pet owners. Some of you out there may even have had a pet pass away while having an anesthetic procedure done, which is truly heartbreaking for all involved, including the doctor and hospital staff.

Anesthesia is not without risk, but mitigating risk is what it’s all about. Older pets can be at higher risk, because of other diseases they may be experiencing and changes in their heart, kidney, or liver function. Younger pets, by contrast, often have far lower risk because they have yet to develop these complications.

But even so, it’s important for any pet to have an updated exam and bloodwork prior to any anesthetic procedure, even something as routine as a spay or neuter. It’s rare, but I have postponed spays and neuters based on labwork findings due to concern about a possible abnormality a pet was born with that we didn’t know about yet, like a congenital liver shunt or kidney disease.

I also think many pet owners feel that we have no control over a pet’s well-being while they’re under anesthesia. Almost like we say a quick prayer, get started, and hope nothing bad happens. But anesthesia is not like this at all. In a hospital setting, a pet’s heart-rate, breathing, blood pressure, and depth of anesthesia are all very carefully and continuously monitored. Any changes in the appropriate and safe patterns for these parameters are addressed long before they develop into serious problems. In effect, we have better “control” over a pet’s vital function while they’re under anesthesia than at any other time.

So while there are of course no guarantees for anything in life, anesthesia is typically very safe, especially for a young pet, when we have reduced risk as much as possible through proper pre-surgical examination, labwork, and careful monitoring.

Also remember that since spays and neuters are very common surgical procedures, that surgical time is also typically short compared to other types of anesthetic procedures. A short surgical time also reduces overall risk. Think again about the risk of performing surgery on a very sick dog with a pyometra, or a 10 year old dog with mammary cancer. The surgical risk is much higher for pyometras and mastectomies and surgical time is doubled, if not tripled.



A Bit on Breeding

A third reason I hear from pet owners why they don’t want to spay or neuter their dog or cat is because they would like to use them for breeding. If this is a pet owner’s goal, I typically make sure they understand the risks posed by not spaying or neutering, and that they have some kind of a plan in place. For some folks, breeding their dog (and yes, sometimes their cat) may seem like a good idea with a healthy financial incentive, but it can become more trouble than expected if you don’t know what you’re doing.

I Should Do What, Now?

The fourth and final barrier I encounter to spaying and neutering is simply a lack of perceived need to do so. Some folks look at it as “unnatural”, others may have grown up with pets that were never “fixed” and just don’t understand the importance. Yet others may have emigrated from another country where spaying and neutering on a widespread scale simply isn’t a thing. For these folks, I simply have to review the points we’ve just discussed in this article, as sometimes just further education on the subject goes a long way.

Please Spay or Neuter Your Pet. It’s Important!

Overall, I do hope this article has been educational and helpful to you. Perhaps it’s cleared up some misunderstandings, or raised some points you hadn’t thought about before. But as always, it’s best to discuss spaying or neutering with your own veterinarian to develop the best plan for your pet.


Posted in

Dr. Chris Vanderhoof, DVM, MPH

Chris is a seasoned veterinarian with over 15 years of animal health experience in small animal, large/farm animal, equine, and public health fields.

About Us

We've taken the guesswork out of caring for your pets. Our formulations are created by experienced veterinarians to address specific solutions for a variety of pet issues.
All of our products are:


As seen on: