What is the difference between spaying and neutering dogs? Why do you do it? Advantages and disadvantages

01/22/2026 01/22/2026

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If you own a dog, you've probably thought about spaying or neutering at least once.

I'd like to write about why spaying and neutering are necessary, the differences between them, and their pros and cons.

What's the difference between spaying and neutering?

Spaying and neutering are two terms, but castration basically refers to the removal of a male's reproductive organs.

Conversely, removing the female's reproductive organs is called contraception.

The terminology is slightly different, but the meaning is the same: removing the reproductive organs.

Benefits of Spaying and Neutering

There are several reasons for spaying or neutering, but here are three of the most common.

① To treat or prevent injury or illness

Removal of reproductive organs may be necessary due to injury or illness.

Removal before disease develops can also prevent the onset of disease. In males, it can prevent testicular tumors and perineal hernias, and in females, it can prevent mammary tumors and pyometra.

Removing the reproductive organs can prevent reproductive diseases, and by reducing male and female hormones, it can prevent hormonal diseases.

② To calm the dog

There is a period in dogs when their reproductive instinct to produce offspring becomes stronger. This is the estrus period.

Males may start howling, become irritable due to changes in hormone balance, or become disobedient.

Females may experience external bleeding and a temporary loss of appetite and energy.

Other than that, for example, while out on a walk, they may jump over other dogs, or sometimes cling to humans and shake their hips.

While this may only happen to family members, it can also cause trouble for other people's dogs, or even injure humans as a result of irritation.

Neutering or spaying reduces sex hormones, leading to calmer behavior.

③ To prevent unwanted breeding

This is probably what many people think of when they hear about spaying and neutering.

Some of you may have had the experience of owning a male and female dog and unknowingly finding one that was pregnant.

If you can keep them or find someone you know willing to adopt them, there's no problem. However, unfortunately, some people are unable to care for them and end up having to send them to the animal shelter.

Dogs sent to animal shelters may be adopted, but if no adoptive homes are found, they will be euthanized.

Approximately 4,000 dogs were euthanized at animal shelters in fiscal year 2020.

Although the number of dogs euthanized is decreasing year by year, some dogs may still be neutered or spayed in advance to prevent such tragic events.

Disadvantages of Spaying and Neutering

The benefits of spaying and neutering are the same as the "Reasons for Spaying and Neutering" above.

So here, we'll explain the disadvantages of spaying and neutering.

① The Act of Surgery is Risky

In the first place, any surgical intervention is inherently risky, and it's not unusual for a healthy dog to experience some kind of abnormality after spaying and neutering.

For example, in females, surgery can weaken the urethral sphincter, which can lead to incontinence.

In addition, infection can occur from wounds after surgery.

After surgery, you should avoid walking your pet in the rain and avoid getting it dirty until the stitches are removed.

② Becoming more likely to gain weight

Neutering or spaying can disrupt the balance of sex hormones, which can lead to a decrease in food intake and exercise, making your dog more susceptible to gaining weight.

A fat dog may look chubby and cute, but being overweight can lead to illness and, especially in older dogs, even be life-threatening.

After spaying or neutering, be sure to carefully manage your dog's diet and provide it with adequate exercise.

③ They may lose confidence or become shy.

This is especially common in males. A decrease in male hormones, which are associated with aggressiveness, can cause dogs to lose confidence or become shy.

This is particularly noticeable in dogs that are naturally timid. Therefore, if you are considering neutering or spaying a timid dog, it is a good idea to exercise them and interact with people and other dogs beforehand to help them build their confidence.

Cases and Subsidies for Spaying and Neutering

Cost of Spaying and Neutering Surgery

Prices vary depending on the breed of dog, but the average cost for small to medium-sized dogs is said to be between ¥15,000 and ¥30,000.

Large dogs tend to be more expensive than small to medium-sized dogs because more anesthesia and medication are used during surgery.

Please note that the above fees are for the surgery alone. Additional costs may apply, such as preoperative testing, postoperative medication, and stitch removal.

Including pre-operative examinations and post-operative care,

For small to medium-sized dogs, it will cost around 30,000 to 50,000 yen
For large dogs, it will cost around 50,000 to 70,000 yen

This is a good guideline.

Subsidies and Grants for Spaying and Neutering Surgeries

Depending on where you live, your prefecture or veterinary association may reimburse part of the cost of the surgery.

Let me introduce some examples.

♦Nagoya City, Ehime Prefecture (2021)

In Nagoya City, Ehime Prefecture

For neutering, Nagoya City provides ¥1,600 and the Veterinary Association provides ¥3,200.
For spaying, Nagoya City provides ¥3,200 and the Veterinary Association provides ¥6,400.

Subsidies are available. However, to receive this subsidy,

The dog must be kept within the city and the owner must reside within the city.
The dog must be registered under the Rabies Prevention Act and reside within the city.

Both of these conditions must be met.

♦Mito City, Ibaraki Prefecture (2021)

Mito City, Ibaraki Prefecture, offers a subsidy of 3,000 yen for spaying and neutering dogs.

To receive the subsidy,

The dog must not be for sale.
It must maintain an address in Mito City even after being neutered.
It must not be in arrears with city taxes.
It must be registered with Mito City and have been issued a rabies vaccination certificate for fiscal year 2021.
The dog must have been vaccinated in fiscal year 2021.

All of the above conditions must be met.

♦Imabari City, Ehime Prefecture (2021)

Imabari City, Ehime Prefecture, offers a subsidy of 2,000 yen per dog for spaying or neutering.

In addition, each household can only receive one subsidy per fiscal year.

To receive the subsidy

The dog must be healthy and kept in Imabari City by an owner with an address in the city.
The dog must be registered and have received a rabies vaccination within the past year.

All of the above conditions must be met.