Top 11 Reasons to Spay & Neuter Your Dog

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Should I Spay And Neuter My Dog?

(Updated in 2023 and continuously updated based on current research)

Before clients look for a spay and neuter clinic, they bring their puppy to me for puppy boot camp training, behavior, and spay/neuter advice.

Spaying and neutering is a hot topic. Almost as controversial as what to feed my dog.

When I first wrote this spay/neuter article years ago the data was clearly in favor of spaying and neutering pets. From a pet overpopulation standpoint, there’s no debate that spaying and neutering dogs and cats reduce pet deaths due to overpopulation in shelters. However, a lot has changed over the years regarding the health implications of castration and I have updated both sides of the debate below.

People get very worked up over the question of whether to spay or neuter a dog. The debate tends to polarize rather than unify pet parents. As with any decision, you must weigh the risks vs. rewards of spay/neuter.

However, make sure your information is accurate, up-to-date, and then examine both sides of the debate. Look for evidence-based research before making spay/neuter decisions.

Here are some of the most popular myths and defenses for not spaying or neutering a dog or cat.

Before I go any further, I’d like to state an axiom and cardinal rule of science when the data changes so does science.  Views and facts are not fixed and absolute. If leaving a dog intact and not spaying or neutering dogs is shown to cause a dog to live a healthier, longer life, I would also change my opinion on the subject. And science changes all the time.

However, it is also imperative to take into account not only the medical evidence (pros and cons) of spay/neuter but the emotional, behavioral, and social implications of leaving a dog intact. Not to mention the added difficulty and mess of dealing with a menstruating dog for several weeks out of the year.

Although there are pros and cons for both neutering and not neutering a dog, the current evidence suggests more health benefits than downsides of spaying and neutering SOME dogs. However, this does not hold true for every single dog, size, sex, and breed.

In some dog breeds, leaving a dog intact outweighs spay/neutering. As the American Veterinary Medical Association (AVMA) states, “there is no single recommendation that would be appropriate for all dogs.” For example, I would think hard about spaying or neutering a Golden Retriever and Labrador Retriever, as the research states the medical downsides of spaying and neutering these breeds far outweigh the upside.

Each parent has to make their own decision and balance those decisions with the health and welfare of a dog and in consideration of the laws. For example in Los Angeles CA, it is illegal to have a 6+ month dog intact unless you have a breeder’s license or some other unique situation.

Also, where will your dog board and stay when you are gone? You will need to find dog boarding at some point in your dog’s life and most dog kennels do not accept intact dogs (for good reason). That’s one of the many reasons I created my Membership Club which is an “anti-kennel & daycare.” Some parents also want their dog to go to dog daycare even if 99% of dog daycares (and boarding facilities) are not healthy for a dog.

In either of these cases, your dog will not be accepted and/or would likely be in danger if they went to these boarding or daycare facilities due to how other dogs respond to intact dogs. Something serious to consider as I wrote about in my dog daycare and boarding dangers article.

When To Neuter A Dog?

When to neuter a dog, at what age or whether to neuter or not, are very important topics. Age plays a large factor in everything from the behavior of the dog to medical reasons to neuter your dog.

At what age a dog is neutered is very important.  When considering at when to neuter a dog it is even more important for service dogs.

In this study of 245 service dogs in a highly controlled service dog breeding and training program, service dogs neutered and spayed between 7 and 11 months of age showed the highest service dog placement rate and lowest service dog dismissal rate than spay and neutering at younger and older ages.

Essentially dogs neutered during the 7 – 11 month window showed the best behavioral results.

However, on the other side of the coin a 2017 research paper consisting of video analysis, case studies and questionnaires shows that there are significant behavior changes in castrated dogs vs. intact dogs.

Medical and Behavioral Considerations

Here is a newer study that looks at many different dog breeds and how spaying and neutering effects each breed.

On the medical side of the equation, we must consider the following debilitating conditions and diseases that may be caused or exacerbated by spay/neuter or too early spay/neutering:

Elbow dysplasia, hip dysplasia, cranial cruciate ligament tear, and/or rupture.

And some cancers that may be caused or exacerbated by spay/neuter or too early spay/neutering include:

Osteosarcoma, lymphoma, mast cell tumor, and/or hemangiosarcoma.

On the animal welfare side of the equation, we must consider these vital factors of not spaying/neutering a dog:  enrichment, behavior, cognition, emotion, and socialization. Listed below are just a few considerations of each that will have to be thoroughly analyzed according to each individual dog.

• A dog’s ability to socialize with other dogs will be limited. For a female dog, she won’t be able to socialize when in heat.
• Conspecific play sessions will be limited to impossible
• Dog’s roaming desires will increase, typically causing leash pulling and difficulty for a dog to work and pay attention to the handler (for service dog training this would be problematic and may cause failure)
• Excess olfactory enrichment and general sniffing that goes along with roaming, and seeking partners
• Less likely to pay attention to the handler as competing biological factors will outweigh training and attention span
• Mounting of other dogs and being mounted (dog humping) will both increase
• Overpopulation of dogs and unwanted dog pregnancies will go up
• Dog Marking and counter-marking behavior will increase (for service dog training this would be a reason to fail a public access test)
• Other dogs reacting negatively to an intact dog causing a chain reaction of poor behavior will increase
• Sequestering a female dog while they are in heat will increase
• The cost and inconvenience of dealing with a female dog in heat for several weeks out of the year will increase
• The behavioral and training implications of not being able to implement a training or behavior modification protocol because of a dog’s sexual/reproductive status will be negatively affected.
• Receiving adequate pet services and support from pet professionals regarding all pet services including most boarding and daycare’s are unsafe options can’t be considered and wouldn’t be safe for an intact dog to attend those environments (for several reasons).

That being said, here are some common myths about why not to spay or neuter your dog.

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Top 11 Reasons NOT To Spay And Neuter Your Pet Dog Or Cat (Debunked)

• It’s Natural – Probably the most common faulty argument I hear from many well-intentioned, smart folks about why to keep their dog’s balls and ovaries intact rather than to spay/neuter is, “my dog’s balls are natural.” While it’s true, that a dog’s balls or a bitch’s menstrual cycle are natural, it’s a moot point in the discussion of whether to spay or neuter a dog.

The logical fallacy is an appeal to nature. Just because something is natural does not mean that it is good, justifiable, inevitable, or ideal.  There are reasons not to spay or neuter your dog, but because “it’s natural” isn’t one of them.

Here are just a few unsavory things that dogs do in nature that intelligent, responsible, caring pet parents do not allow: Coprophagia (eating poop), eating the placenta after giving birth (yummy), having sex with siblings, relatives and parents (incest), eating foods and plants that will kill a dog or cat, cannibalism, and sex without consent are all-natural dog behaviors, however, these are not behaviors we condone or allow.

In fact, many dog breeds would not even be able to procreate without the advent of science and human intervention. These dogs are about as natural as Splenda and the, “it’s natural” argument is faulty.

• Appeal to Emotion – In this argument, I hear, “How could you possibly let your dog live without his testicles or ovaries! That is so cruel to steal your dog’s ability to reproduce! Think about doing that to your husband, wife, kids, and the mental torment they would be in so I would not dare do that to my dog or cat.”

False. Does this sound rational to you? Any attempt to manipulate an emotional response with anthropomorphism sprinkled on top in place of a valid or compelling argument is an appeal to emotion, not an argument worth defending or having.

• There is no medical evidence that removing a dog’s testicles or having a dog spayed is medically healthy for them. – False (some of the time). Actually, there is scientific evidence that having a dog’s testicles removed may extend your dog’s life by close to 2 years.

Of course, it also removes the possibility of some types of cancer as well (only in some dogs. However it may RAISE the possibility of cancer and other health issues in some dogs). The caveat is, there is contradictory information based on a variety of factors, so each breed, sex, size, hereditary, and congenital lineage should be individually evaluated.

As mentioned earlier, spay and neutering Labradors and Golden Retrievers are more dangerous than healthy and are shown to be detrimental to those breed’s medical health. So do your research, as with life, research doesn’t sit still and changes all time.

• My dog is not allowed to hump other dogs so there’s no need to spay/neuter – False. Yes I realize that many people think they have the best-behaved dog that is perfectly socialized, obedience trained and that defies all innate canine traits and behaviors such as dog mounting/humping, chase reflex, puppy biting, dog barking, etc. But people make mistakes.

When (not if) we drop the leash, take a dog to the park, travel, open the front door, etc, and the dog sneaks out, or when the dog opens the door themselves when we have company come over, or a doggie play date, etc, accidents do and will happen because we’re human.

If you think it takes your dog the same amount of time as a person to copulate and ejaculate, think again, it takes only a split second. Male dogs don’t try to “hold-out” for their partner’s pleasure or have performance anxiety.

Before you notice your perfectly behaved dog was even gone or could call Rover’s name, he could have impregnated a bitch in heat.

In addition, unaltered dogs, particularly males, will chew through a leash, jump a fence, dig under a fence, breakthrough screens, or even mate through a chain-linked fence! And even if your pet is safe in your yard, it doesn’t mean that another roaming animal won’t come and join them – kinky!

You don’t need me to tell you, look at your local shelter! It is impossible to monitor your dog every second of the day. Even if you are taking care of your pet and socializing, dog training, and enriching their lives, you cannot possibly watch your dog every second of your life. That one second you don’t watch them is all it takes to reproduce. This fact alone warrants fixing most pets.

• My dog is friendly, submissive, and not aggressive to other dogs – Irrelevant. Dogs do not live in a vacuum. Being unaltered isn’t always about how well-behaved your dog is to others but how other dogs behave in the presence of your dog. You could argue that isn’t your problem but it’s worth considering the following.

An unaltered dog will set off the chemistry in a dog park, playgroup, doggie daycare, boarding facility, or any passerby on the street. Male dogs can smell a bitch in heat miles away and will seek her out as a biological and behavioral reflexive response.

It is incredibly unhealthy and devastating to sequester a healthy dog, but you also don’t want all the neighborhood boys trying to mount your bitch. This is why an intact bitch can not go to a traditional dog boarding facility, dog daycare, or a fenced-in dog park (nor would you want them to.)

If you want to enrich your dog’s life by socializing her and allowing her to have play sessions and to live a normal life of a dog, I strongly consider having her spayed to make life easier and less stressful for your dog and you. It isn’t solely about the way your dog reacts to other dogs but how other dogs react to your unaltered male/female.

This is also why unaltered dogs are smartly not allowed to leave any shelter, adoption, or rescue agency intact. Intact dogs set off the chemistry of other dogs they come into contact in a negative, unhealthy, unfriendly way. Otherwise, friendly fixed dogs will likely become aggressive, territorial, possessive, hostile, controlling, unruly, competitive, etc. Just like some human men get around women.

To fully comprehend why this occurs, you must understand the capabilities of a dog’s nose. It is thousands of times more sensitive and acute than our nose.

Parents of domesticated dogs shouldn’t purposefully upset/disturb other dogs’ olfactory glands. When a dog is intact they are chemically omitting pungent, intense smells that stun or stop other dogs in their tracks from several miles away.

Just because we don’t smell the pool of chemicals emitted from your dog’s intact testicles or ovaries other dogs do. Just as we may be disturbed when we walk past someone who reeks, a dog is equally disturbed when they smell a pool of chemicals emanating from an unaltered dog many city blocks away.

The smell difference between an unaltered dog and an altered dog is substantial, and other dogs are equally disturbed being around unaltered dogs as we are disturbed by someone next to us who smells wretched.

• My dog should give birth to at least one litter – This deserves the jaw-dropping award. There is no scientific evidence that shows that giving birth to a litter is either healthy or extends a dog’s life. A dog does not think like a person and does not want to have babies of their own to feel fulfilled or to take care of them when they get old. And until your dog speaks and tells you this directly, let’s just leave it at that.

• My pet will get fat and lazy after being spayed or neutered – False. Unsubstantiated myth. Weight is directly correlated with intake, exercise, and metabolism. All change over the course of a dog’s life. Feed your dog healthy food, and dog treats, exercise, socialize and enrich them daily and weight will likely not be a problem.

However, neutering your dog will attenuate their tendencies to wander and roam looking for a mate and will also cause them to get into fewer altercations, keeping them safe from cars and lessening the likelihood of impregnating a bitch while on the hunt. Which is a good thing.

• We want another pet just like our dog Bella – Ignorance. For example, I am so different from my parents and siblings you wouldn’t even think we are related. Even when breeding purebreds with known ontogenies, health, temperaments, hereditary and congenital factors, rarely are the offspring even similar to the parents’ looks or behavior.

Your chances of getting a dog just like your current one are Slim to none, and Slim just left town. Sentient beings are unique individuals and are always comprised of phenotype and genotype. I guarantee you will find the pet of your dreams at your local shelter.

• My pet’s personality will change – False. This belongs in the WTF category as well. If anything, your pet’s temperament will change for the better after a dog is spayed/neutered. Your dog’s drive to mate will decrease, thereby decreasing, humping/mounting, roaming, fighting, and competing for bitches.

Your dog will also stop trying to control and urine mark territory everywhere they go leaving them a lot less stressed.

Richard Bowen, DVM, Ph.D. a professor at the Animal Reproduction and Biotechnology Laboratory of Colorado State University states “neutering reduces aggression. The earlier you can neuter, the fewer aggression problems you’ll have. Roaming around, urine-marking, sexual behavior toward people and other animals… Most of those behaviors are dramatically decreased.”

While it is overly simplistic to state that altering a dog will reduce aggression, since Certified Dog Behaviorists and Trainers define behaviors as verbs, not as labels, neutering does generally help with aggression.

Neutering doesn’t directly reduce or cause aggression, although it does tend to reduce conspecific dominance and precursors to unhealthy, unwanted behaviors that could easily elicit reactivity and conflict with another dog/s.

• My dog stays at home and is potty trained so there is no need to spay/neuter – First, that is very sad that your dog doesn’t get enriched and outside often. Besides this obvious animal welfare problem, the statement is False.

If your dog doesn’t get out much you are certainly not taking care of your dog and not fulfilling your dog’s social, emotional, mental, and physical health. Neglecting any aspect of your dog’s comprehensive health is a poor decision and irresponsible.  I have seen many dogs mating through fences. Where there’s a will there’s a way!

Spaying and neutering decrease a dog’s desire to roam in the search for mates, marking behavior, and territorial desires. Dogs who are spayed and neutered do not try and claim everything as theirs (resource guarding) and are much more socially appeasable and amenable. Don’t confuse luck with intelligence, just because it hasn’t happened yet doesn’t mean it won’t. Don’t become another statistic at the expense of your pet and their future puppies.

• Tradition – In my country, we don’t spay or neuter dogs or cats.  While true, Europe and other countries do not spay and neuter their dogs nearly as much as we do in the United States, it is also true that in these countries many of the dogs are homeless, stray or community dogs, live much shorter lives, are less taken care of, may not have access to health care and are not domesticated house pets as they are in the United States.

However, I do believe that we need much more education, dog training, regulation, and laws protecting animal rights in the world. Regulating dog training and the licensing of pet parents would go a long way towards respecting animals and not having to spay or neuter pets.

It’s important to remember that just because something is a tradition doesn’t mean it is healthy or shouldn’t be questioned. On both sides of the debate. Many traditions are neither ethical nor condoned, like slavery, homophobia, racism, discrimination, ear cropping, tail docking, and bigotry just to name a few, and are not practiced by anyone who is compassionate, caring, or fair.

Pro Tip: Want to spot a Service dog or Therapy Dog that might be fake? In most cases, both are spayed and neutered. Also, almost all Emotional Support Dogs are spayed or neutered. Many of the behavioral reasons are listed above. Most service dogs, emotional support animals, therapy dogs and/or canine good citizen dogs are spayed and/or neutered.

In addition, most cities such as Los Angeles does not allow dogs to remain intact under most circumstances and many apartment buildings, homeowner associations, and co-ops will not allow intact dogs to live in pet-friendly apartment buildings near you.

The United States kills over 4 MILLION companion animals every year – True. The United States shelter system has more than 10+ million dogs and cats come through their doors, and many don’t make it out!

Many of those millions of pet parents and puppy mills neglected their responsibilities and didn’t have their pets spayed or neutered and allowed their pets to reproduce.

Shelter dogs are the result of poor behavior and failing to spay and neuter pets. Consequently many will end up being killed and also costing taxpayers millions. Studies show that over 50% of these homeless dogs and cats were not planned. The parents of unwanted puppies and kittens were all defenders of leaving their natural dog testicles and ovaries unaltered. So please be a responsible pet parent, and if it is safe for your dog, spay and neuter your dog, and adopt don’t shop.

Dog Neutering and Spaying Conclusion

There is no grand conspiracy to steal a dog’s reproductive ability away, and this is not about a person’s pride (dogs don’t have pride). There is currently no one size fits all answer. There are some compelling reasons to spay and neuter your dog and cat and also some compelling reasons not to spay/neuter.

Even though there is evidence that dogs that are spayed and neutered are less stressed, and may live longer, other studies show the health problems emanating from spaying and neutering some breeds. Those organizations like the Association of Shelter Veterinarians (ASV) associated with high-volume intake shelters have a different opinion than other organizations that are focused on the medical health of animals.

Regardless of a parent’s decision to spay or neuter, we have to weigh the pros and cons of any medical procedure. It is our responsibility to not view this topic myopically just through a medical lens but instead view spay and neuter through the lens of complete care of our domesticated dogs’ needs: behavior, enrichment, socialization, play, training, nutrition, shelter, physical and physiological health.

Domesticated dogs are not pack animals, wolves or carnivores and until this changes and dogs go back to living in the wild without the advent of human intervention, let’s do best by them and thoughtfully weigh the risks and rewards of spay and neutering.  In order to do this, we need to stop with arguments based on the naturalist fallacy, appeal to emotion, and other arguments that don’t help pets. We need to do what is in our pets’ best interests.

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