Ultimate Dog

By Luna Lupus - Reading Time: 22 minutes
Neutering/spaying your dog

Spaying and Neutering: All the Knowledge You Need for an Informed Decision

One of the most important (and perhaps most difficult) decisions that we have to make as dog owners is whether or not we're going to spay or neuter our dog. If we decide to do it, the decision is irreversible. If we decide not to do it, we can change our minds at a later time, but each year we wait has its cost. Either way, this is not an easy decision to make, and you shouldn't be taking it as such.

Feeling the weight of its responsibility is, I would argue, a healthy thing. There is a sea of information out there about the dangers and benefits of spaying and neutering, putting any dog owner into a conflicting position after having read some of the online sources. Who can we trust? Why do two vets say completely opposing things? Can we trust our friends who had good or bad experiences with spaying or neutering their dogs?

It appears as if there are two camps and you have to pick a side – you are either pro neutering, or you are against it. You will definitely spay your dog, or you could never do it. But the reality is much different than that. In reality, many dog owners make their decision and feel insecure about it. They question it at a later time, they don't know how to find credible information, they struggle understanding medical terms and research.

The goal of this article is to help you make an informed decision for your dog and your dog alone. You will find enough information from credible sources to weigh your options and make a confident decision that you won't have to question.

Male Dogs 

What is neutering?

Neutering is a surgical procedure done to a male dog that results in him being unable to reproduce. During the operation, both of the dog's testicles are removed, taking away his main source of testosterone. This procedure is also known as castration and is done under general anesthesia.

There is also the less-known option of canine vasectomy. This is an operation in which a section of the vas deferens (the tube that carries the sperm from the testicles) is removed, making the dog infertile. The dog's testicles are not removed, and therefore his testosterone levels aren't impacted. Any behaviors or conditions related to testosterone will not be altered, meaning your dog will still be drawn to females in heat – he could mate with them, but won't be able to get them pregnant.

What are THE PROS of neutering?

Neutering has several benefits for your male dog and your mutual life together. Those benefits can be observed on a behavioral, physical, and societal level.

Behavioral pros of neutering are related to the absence of behaviors triggered by your dog's breeding instinct. A neutered dog is less likely to engage in humping and over-marking his territory with urine. He also won't have a reason to run off after a female dog in heat, making him more attentive to you outside as his primal instinct to breed won't be taking over.

He will not see other male dogs as his competitors and therefore, won't engage in aggressive behaviors with the intent to assert his dominance over other male suitors. It is important to note here that if some of these behaviors are already developed before the neutering, the neutering itself may not be able to eliminate them completely.

With that said, neutered dogs have been observed to be more trainable than intact dogs, have better recall, are more playful, and less likely to develop separation anxiety.

Physical pros of neutering are related to the prevention or elimination of medical conditions in the dog's reproductive organs. Neutering your dog prevents him from developing testicular cancer, which is the second most common tumor found in dogs.

Another very common condition that neutering protects your dog from is a prostatic disease called benign prostatic hyperplasia (BPH). It's a condition where testosterone causes gradual prostate enlargement. As a result, the dog experiences pain and discomfort when peeing. In one study of 300 intact dogs, 231 (63,4%) were found to have this condition. The chances of BPH significantly increase with age, and studies have shown that half of all intact dogs will develop it by the time they are only three years old. When an intact dog reaches nine years of age, his chances of BPH are 95% to 100%.

The societal benefits of neutering are associated with controlling the animal population. In the US, approximately 6 million animals are surrendered to shelters every year. Only about half of them actually make it into new homes, meaning the number of euthanized animals within the shelter system is very concerning and scary. As dog owners, it's our responsibility to make sure we're not contributing to the problem of overpopulation.

Intact male dogs have been known to wander off or escape from their backyards, driven by the scent of a nearby female dog in heat. Because it takes two to get pregnant, both dog owners carry the responsibility for it, not just the owner of the female dog. By neutering your dog, you are ensuring that he can never participate in making an unplanned litter of puppies.

A US study found that more than 50% of all researched litters were unplanned. Other studies have shown that the majority of dogs who are surrendered to shelters are intact. The jury is still out on specific reasons as to why this is so, but the researchers believe there is a correlation with behavioral issues.

What are THE CONS of neutering?

Similarly, as with the pros, the downsides of neutering can be observed on a behavioral and physical level. There doesn't seem to be any known societal downfalls.

Several studies have shown a correlation between neutering and certain medical conditions. Scientists believe this is due to disruption in the dog's hormonal system, as research has shown that sex hormones have a significant impact on the immune system.

Hormones regulate dog's body, and if too much or not enough (as in the case of neutering) hormone is produced, the system is disrupted, which affects the body as a whole. For example, prostatic tumors affect about 0.2% to 0.6% of dogs, but neutered males have a higher risk for such tumors than intact dogs. There is also an increase of chances for hypothyroidism and bone cancer (osteosarcoma) in neutered dogs, especially if the breed itself already has a predisposition to it.

A study of 90,090 veterinary patient records (spanning over 15 years) revealed that neutered dogs have a higher risk for autoimmune diseases. Neutered dogs have an increased risk for a cardiac tumor as well – they are two times more likely to develop it than intact males. Finally, castrating your dog puts him at risk for obesity – one study found that 34% of neutered dogs showed signs of being overweight.

Some findings suggest that dogs neutered before five months of age have decreased chances of obesity than those neutered later in life. Sexual hormones are a very important part of development, especially for the long bones, which explains why neutered dogs are at risk for orthopedic problems. Dogs who are neutered before puberty tend to develop more issues with their joints and bones later in life. Males that were castrated before they were five months old are much more likely to have hip dysplasia and the rupture of the cranial cruciate ligament. In the case of bone cancer, studies have shown that dogs neutered before they were one year old had significantly higher chances of developing osteosarcoma. 

Possible behavioral cons of neutering are related to a dog's temperament, fearfulness, and aggression. Studies have found that neutered dogs tend to have higher noise-sensitivity and display fearful behaviors towards strangers. Castrated dogs tend to be less bold than intact ones.

They display shy behaviors, but their fear often turns into an aggressive response. They are mainly hostile towards strange people and dogs, but also tend to be more vocal and excited. Researchers believe this is due to many dogs being neutered before they reach puberty, as a sexually mature dog is less fearful and more self-assured.

There is a strong probable cause to believe that dogs neutered before reaching puberty display more undesirable behaviors, but the studies that researched these behavioral patterns regrettably did not distinguish between dogs who were neutered before and after puberty, so we have to be careful before making hasty conclusions. When speaking of male dog aggression, we also have to be aware of the fact that male dogs display more aggressive behaviors than female dogs in general – some studies attribute 70% of bites to male dogs.

Female Dogs 

What is spaying?

Spaying is a surgical procedure done to a female dog in which her reproductive organs are removed. In most cases, the ovaries and the uterus are both removed, and this type of surgery is called an ovariohysterectomy. When only ovaries are removed, the surgery is called an ovariectomy. In both cases, the female dog cannot reproduce anymore, nor does she experience a heat cycle (also called estrus).

What are THE PROS of spaying?

The greatest benefits of spaying your female dog are physical benefits, as spaying protects her from some common and potentially life-threatening conditions. Mammary tumors are the most common tumors in female dogs and the most malignant ones at that (meaning, many of them are cancerous – around 50%). Mammary tumors present a serious life-threatening risk to female dogs. One study found that 59% of dogs with a mammary tumor had to be euthanized. An intact female has a 7-times greater chance of developing mammary tumors than a spayed female, especially in their old age.

The most common age of diagnosis is ten years old, and while curative spaying is possible, it's important to note that putting your dog under anesthesia at that age isn't without risk. The older the dog is, the greater their chances of not waking up from anesthesia. The earlier the dog is spayed, the lesser the risk of a mammary tumor – those who are spayed before their first heat only have a 0.5% risk for a mammary tumor.

In comparison, those who are spayed after two heat cycles have a 26% risk. Another dangerous condition for intact females is a uterus infection, also known as pyometra. By the time they are ten years old, 24% of female dogs will develop this condition, especially those who have never had a litter, as the risk for pyometra is lesser if the dog has been pregnant before. An emergency spay surgery is necessary to treat this condition, but as mentioned before, the risk of the operation is higher when the dog gets older.

The final physical benefits are related to the absence of a heat cycle. Most female dogs go into heat approximately two times a year, but this varies based on breed and size. The outer and obvious signs of estrus are the swelling of the vulva and a bloody vaginal discharge. This is a time in a dog's cycle when she is ready to mate and can become pregnant. As a result, she might be peeing more often (as a way to attract males, since her urine is full of hormones and pheromones), or may even start urine-marking within the house.

Dogs pick their mating partners only based on sexual instinct, so a female (if left to her own devices) may breed within her own family lineage – for example, with her son, father, brother. On average, a female dog will be in heat up to two weeks, but the length may vary from dog to dog. Some female dogs also experience silent heats, meaning their symptoms aren't obvious, and the owner may not even realize that their dog is in estrus.

They can also experience a false pregnancy, which is when the dog acts as if she is pregnant and experiences some pregnancy symptoms, such as lactation, without actually being pregnant. False pregnancy is believed to be caused by a hormonal imbalance, and the symptoms can last more than a month. (It is responsible to note that some female dogs still experience it despite being spayed, usually a few days after the operation, due to a change in hormone levels).

Spaying also has several behavioral benefits, closely tied to the absence of the heat cycle. When a female dog is in heat, her behavior may suddenly change. She can become erratic due to the hormonal changes and possible pain. She is highly more likely to take off or escape from your backyard, driven by the instinct to mate. Other dogs will also be drawn to her, and you may find yourself followed by some very persistent male suitors who will not be so easily “shooed” away.

This can cause your female dog significant stress, either because she'll want to mate and won't be able to, or because she won't like the attention of male dogs who will attempt to mount her. If you have several dogs living together in one household, spaying your females might ensure a more harmonious cohabitation – the females won't feel the need to compete with each other during their estrus (dogs living in the same household are known to have cycles in sync) and your male dogs (if intact) will not be at risk to get your female dog pregnant.

A perhaps unexpected benefit of spaying your dog is financial. Managing a dog in heat can cost you every six months – your dog may need to wear pads for the blood discharge, or you might have to use a spray that neutralizes her scent to ward off unwanted male dogs. Having an unplanned litter of puppies is another financial burden alleviated by spaying. There will be high veterinary expenses, and some pregnancies (and births) can have complications. Also, taking care of a litter is very pricey and not something that you should be taking on without planning ahead.

Finally, there is the societal pro to spaying: reducing the number of unwanted litters. As already mentioned previously in this article, millions of dogs get euthanized within the rescue system every single year, just in the USA. Spaying your dog, if you are not a breeder and do not plan to have a litter, ensures you are doing your part in controlling animal population.

Most owners think an unplanned litter could never happen to them, but many of them are wrong and ultimately very surprised when it does happen to them. The number one reported reason as to why their dog got pregnant by accident is that the owner didn't know their dog was in heat. 57% of owners didn't know their female dog goes into heat twice a year.

You may also believe that if your dog had a litter, you'd be able to find good homes for the puppies – but who ensures they won't be breeding further? Who ensures your dog's puppies' puppies will go into good homes as well and won't end up in a shelter? As any ethical breeder can tell you, breeding is a very serious responsibility and should not be taken lightly. Your dog is not just having a few cute puppies – she is bringing new dogs into the world that might one day end up euthanized in a shelter.

What are THE CONS of spaying?

There are several physical cons of spaying your dog that you should be aware of. Obesity is one of the most common ones, as 38% of spayed females show signs of obesity, putting them at greater risk for other health issues connected with being overweight. Whether the age of spaying plays a role here is unclear so far, but it has been proven that spayed females have an increased appetite and are less picky about food. This is likely because, in intact females, estrogen acts as a satiety factor.

Spaying your dog also puts her at potential risk for orthopedic issues. Since sexual hormones are very important for the development of healthy joints, spaying your dog before she reaches sexual maturity can result in orthopedic problems later in life, most notably hip dysplasia and cranial cruciate ligament injury (hormones are believed to affect joint stability).

There is also an increased risk of urinary tract infections, as spayed dogs tend to develop incontinence more often than intact ones. Hypothyroidism, lymphoma, and cardiac tumors were also found to be more prevalent in spayed female dogs.

The behavioral cons of spaying can be observed in some dogs as well. As with neutered dogs, spayed females display more fearful and noise-sensitive behaviors. They are likely to be more reactive towards strangers (both dogs and humans) and have also been found to show more aggressive behaviors towards family members – scientists cannot pinpoint a definite reason for this, but speculate it may be due to a decrease in estrogen and oxytocin, which have been known to protect against anxiety.

How to Make a Decision? 

Some might say weigh the pros and cons as if it's the easiest thing in the world. For many dog owners, it's just not that simple. How do you know which pros outweigh the cons and vice versa? The first thing you should know before you decide whether to spay or neuter a dog is that you are making a decision for your individual dog, your individual situation, your individual family. Your neighbors and friends, however well-meaning, do not know your situation as well as you do, and therefore their opinion shouldn't be your main compass when it comes to this decision.

The second thing to remember is that you are making a decision, not picking a side in a polarizing topic. If you decide to spay your dog, that doesn't mean you automatically think all females should be spayed. If you decide to leave your male intact, it doesn't mean you are anti-neutering. You have a responsibility to your dog, to make a decision that will protect his or her quality of life – but the opinions of other people are not your responsibility. Here are some things you want to consider as you are contemplating this decision:

Money – know your budget. What is the best financial investment in the long run? How much would your intact dog cost you yearly? How much would a potential litter cost? How much would a spay or neuter operation cost? If there are incontinence (or other) problems after a spay operation, can your budget cover them? Can you afford regular vet check-ups for intact dogs to ensure their reproductive organs are staying healthy as they age?

Personal needs – it's not a selfish thing to consider your own needs in this. You are the owner, and you'll be taking care of your dog, so it's only fair that your needs and capabilities play a factor in this decision. Do you have the time and energy for taking care of a dog in heat twice a year? How much time can you dedicate to training an intact male? Do you live with small children or frequently invite guests to your house? Would that be a problem if your dog's temperament were to change after the spay or neuter operation? Have you ever had a dog pass away from a mammary tumor, and you're afraid it will happen again, so you just want peace of mind? All of these are valid factors and valid reasons. They are YOUR reasons, and this gives them all the validity they could ever need.

Your individual dog – how old is your dog? What are your future plans with them? Do you intend to breed them, do you want to engage in dog sports, will they be a working dog or a family pet? What is their temperament right now? How is their health? Every dog is different – when making this decision take into consideration their age, temperament, health, and future. If you have more than one dog, you might even find yourself making different decisions for each dog in the household.

I've decided to spay or neuter my dog – now what? 

After you're sure that you want to spay or neuter your dog, you must decide at which age to do it. There is a lot of conflicting information out there on this. As mentioned, studies show that early spaying in females significantly lowers the risk for mammary tumors, but other studies show that spaying or neutering before puberty has many downfalls for the dog's bones and behavioral development.

Dog owners usually ask their veterinarian for advice on this matter, but there is no consensus among veterinarians on what is the best age to spay or neuter a dog. Most studies (especially behavioral ones) haven't differentiated between dogs that were spayed/neutered before and after puberty, which makes their findings inconclusive.

The studies that did consider the dogs' age show that juvenile spaying and neutering has more cons than pros. The downfalls far outweigh the few possible benefits, which really come down to a game of chance. The decision is still yours, and your veterinarian's opinion on this does matter, since they know your dog's medical history and can follow their development.

But it's safe to say that the bulk of all research shows that you should wait before you spay or neuter a dog until they have reached sexual maturity. This will ensure that your dog is properly grown-up, both physically and mentally!

Another thing to consider is the cost of the operation. The prices of spaying and neutering vary from vet to vet. A spay operation tends to be more expensive than a neuter operation, because it is far more complex and the inner organs are removed. The surgery is also cheaper for smaller dogs than large dogs. In general, the prices are around 300$ or more, but if your budget doesn't cover this or you are in a tight financial situation, there are low-cost options available as well.

There could be a low-cost clinic in your area – if you live in the US, use the SpayUSA's database to find it. Please remember that low-cost does not mean low-quality! Be open with your veterinarian, tell them your concerns, and ask what is included in the procedure. If you don't live in the US or can't find a low-cost clinic in your area, reach out to animal rescue organizations or shelters. They will likely be able to help you out or point you in the right direction! 

The final thing to know about spaying has to do with the procedure itself and post-operative care. Many dog owners have concerns because of anesthesia, and yes, putting your dog under anesthetic does carry a certain risk, but if the animal is healthy, the risk is minimal.

A study of 98,000 dogs showed that the anesthesia-related death rate is at 0.15%. More than 99% of canine patients survive anesthesia. Dogs included in the study were eight years old on average. It's very important that your dog is fully examined before receiving anesthesia and that you closely follow the vet's instructions in the days leading up to the operation!

As for post-operative care, you should be planning your dog's recovery before he or she has the operation. In the week that follows the surgery, you'll need to keep a close eye on your dog. You have to stay at home with them during the day or ask a family member to help out. The recently spayed or neutered dog should not be running or jumping – that includes jumping on/off the bed and couch. Rest is very important for a good recovery, and exercise will be impossible or highly limited, so have a few enrichment toys at the ready to mentally stimulate your dog during rest time.

To ensure everyone's safety, keep the operated dog separate from the other animals (and kids) in the household until they fully recover. Because their stitches might hurt or itch they'll feel compelled to lick and scratch them, which can seriously open and damage the wound – it's important they are always under supervision until their stitches are fully taken out. You will need to check their stitches every day to make sure everything is healing properly. The incision needs to be kept dry, which means no walks in the rain and no bathing until the dog is completely recovered. If your dog is in pain, the vet will likely prescribe pain medication, but you should also consider CBD to alleviate the pain.

Finally, keep a close eye on your dog's behavior and responses. If you see that they are not eating properly or are vomiting, lethargic, etc. call your holistic vet immediately. Keep your vet's phone number in a quickly-accessible and visible place (especially if someone else is babysitting the dog), in case of emergency. 

I've decided NOT to spay or neuter my dog – now what? 

If you've never had an intact dog before, schedule an appointment with a positive reinforcement dog trainer that will help you with a training plan for your dog. It's crucial that you put extra work in the recall training and making sure your dog knows how to keep their attention on you when the situation calls for it.

Remember, intact dogs can feel compelled by their sexual instinct to quickly wander off, but this does not mean they are untrainable! If you can train your dog to listen to you despite their other instincts (for example, prey drive), you can absolutely teach them to listen to you despite being intact – but you will need professional help if you've never done this before.

If your dog is a female, speak to your vet about tracking her estrus cycle. Don't let her off the leash when she is in heat and stay away from dog parks or other places with a lot of off-leash dogs (both male and female). Prepare ahead of time for managing her heat, for example, keep a few extra diapers or pads at home, as the cycle can be irregular for the first two years and can surprise you. If you have an intact male, please be respectful towards other female dogs and their owners – your dog might run up to a female dog in heat, and it's your responsibility to keep him on the leash so that he cannot harass the other dog.

Finally, schedule yearly veterinary appointments once your dog reaches 8 years of age. While this is good advice for all dogs, it's especially crucial for intact dogs who are at risk for developing mammary tumors or prostate problems. With regular check-ups, your vet will be able to find changes as soon as they appear, which will make managing a potential condition much easier than suddenly facing an emergency because something went unnoticed. Having an intact dog is not as much work as it may initially seem, but it's important to have a solid routine in place and a good support system of professionals you can lean on.


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Dr. Zeltzman, Phil. “How Safe is Anesthesia for Your Pet?” Pet Health Network. 

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McGreevy, Paul. Wilson, Bethany. Starling, Melissa. Serpell, James. “Behavioural Risks in Male Dogs with Minimal Lifetime Exposure to Gonadal Hormones May Complicate Population-Control Benefits of Desexing.” Public Library of Science (PLoS), 02/05/2018. 

Llera, Ryan. Ward, Ernest. “Prostatic Disease in Dogs.” VCA, 2018. 

Llera, Ryan. Yuill, Cheryl. “Estrous Cycles in Dogs.” VCA, 2018. 

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Neutering or Vasectomy for Your Dog.” Veterinary Village. 

Kemppainen, Robert. “Introduction to Hormonal Disorders of Dogs.” Merck Manual, Veterinary Manual. 

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Luna Lupus

Luna’s passion for learning about canine psychology and behavior began when she adopted a severely reactive puppy from a local shelter. She is now a big advocate for positive reinforcement and compassionate training. As a writer, she strives to spotlight the topics that fly under the radar and be the voice for all who cannot speak for themselves.

2 thoughts on “Spaying and Neutering: All the Knowledge You Need for an Informed Decision”

  1. Thank you for letting us know that spraying our female dogs can help protect them from common life-threatening conditions like mammary tumors since an intact female has 7 times more chances of developing it than a sprayed one. I recently adopted one of my sister’s dogs, and I was thinking of getting desexing done for her. I’ll keep this in mind while I look for a vet nearby that offers services for pet desexing soon.

  2. Thank you for explaining that spaying can help with preventing breeding with their family that may be with you. I’ve been wondering if we should spay our dog. It seems like it could be a safe option to consider.

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