How Does Neutering Affect a Male Cat?

Neutering is recommended by most vets and can guard against illness as well as preventing male  felines from producing unwanted kittens.

Following the procedure, a neutered cat will exhibit certain behaviors over the short and long term.

He probably won’t roam as much, get into as many fights or be as aggressive. Spraying should also be less frequent.

So that you’re able to provide the best care, it’s a good idea to familiarise yourself with these.

Let’s take a closer look at some of the effects of neutering by answering some common questions relating to post-op behavior.

What are the Initial Side Effects of Neutering?

While the actual neutering procedure is straightforward, an anaesthetic will be necessary.

Resulting side-effects can include tiredness, diarrhea, nausea and sometimes vomiting.

Your cat may also sleep more than usual as the anaesthetic slowly wears off.

Post-Operative Symptoms

  • Aggression
  • Diarrhea
  • Grogginess
  • Excessive Sleep
  • Nausea
  • Vomiting

How Long for a Cat to Act Normal after Being Neutered?

Most post-operative symptoms are perfectly normal and usually recede within 48 hours.

By this time, the anaesthetic will have worn off so your pet shouldn’t be as sleepy either.

If after 72 hours, your cat continues to exhibit some or all of the post-operate side-effects mentioned above, contact a vet.

Try not to worry too much though. The healing process can sometimes take up to 14 days to complete.

Will My Cat Be Aggressive after Being Neutered?

In the early stages of recovery, it’s possible that your cat will be aggressive due to discomfort.

This is an instinctive self-protective behavior – it’s your cat’s way of saying ‘stay away’ and ‘don’t touch!!”

As he begins to feel more comfortable, his aggression should go away.

How Long for a Cat’s Hormones to Balance after Neutering?

Although castration removes the male hormones, they can still take up to six weeks to work their way out of the cat’s body.

Thus, your cat’s behavior may continue to be affected by residual hormones for a short time.

Cat Hissing

Why is My Cat Still Aggressive After Neutering?

In the long-term, neutering is usually really effective at stopping inter-cat aggression, whether territorial or sexual.

But sometimes, male cats will continue to exhibit aggressive behavior long after they’ve been neutered.

This can sometimes occur with cats over two years of age. It’s thought that habit can play a part here.

Remember too, that cats are instinctively territorial. So if another feline invades their space, they may still show aggression, whether neutered or not.

Why is My Neutered Cat Mounting Other Cats?

According to experts, unwanted behavior such as rapacious mounting ceases for about 90% of neutered cats.

But for a small number of felines, this continues and is often caused by stress or because the cat is trying to re-establish his status.

Urinary tract infections and boredom are also known to be causes of mounting.

Do Neutered Male Cats Still Want to Mate?

A small proportion of neutered cats (around 10%) still want to mate with females after being ‘fixed’.

As put by respected veterinary behaviorist, Dr Nichold H. Dodman, on the Tufts website:

“Owners should know that in some cats, neutering does not completely turn off the sexual lights. Instead, the procedure sort of turns the dimmer switch way down, but there’s still enough of the male behavioral instinct remaining to be problematic.”

How Do Male Cats Behave After Being Neutered?

Most of the time your cat’s behavior will improve. Here are some typical examples of the positive impact of neuteuring.

Cat Roaming by Car

Less Roaming

A neutered cat doesn’t usually roam as much because he’ll no longer have an urge to seek out a female.

So there’s less chance that he’ll put himself at risk in pursuit of a mate – bear in mind that toms often brave busy roads in their desperation to reach the object of their affections.

Nor will a neutered cat feel any particular pressure to mark his territory as much. This means less fights and confrontations with rival males.

Cleaner Home

You should also reap the benefits of a more laid back cat around the house.

His indifference to territory-marking potentially means that he won’t spray as much indoors or around your garden.

Calmer, More Affectionate

A lot of owners report that their neutered cats are more affectionate and calmer. As already seen, this is due to the eradication of the hormone, testosterone.

Weight Gain

Because a neutered cat expends less energy in seeking a mate, it’s possible that he’ll still consume the same amount of food. This potentially means that he’ll burn off fewer calories and gain weight.

Sleeping Cat

More Sleeping

Neutered cats tend to sleep more after being neutered, both immediately following the operation and in the longer term.

Neutering Pros

  • Less Roaming
  • Less Fighting with Other Cats
  • Less Indoor Spraying
  • Calmer Cat
  • No Risk of Unwanted Kittens
  • No Risk of Prostate or Testicular Cancer

Neutering Cons

  • Weight Gain
  • Doesn’t Always Work with Older Cats

Do Male Cats Change After Being Neutered?

Despite some of the behavioral changes already mentioned, a cat’s temperament doesn’t change after being neutered.

Personality and temperament are the result of neurological factors, as well as genetics and developmental experiences.

Castration affects behavior, nothing more.

Do Cats Know They’ve Been Neutered?

There’s an awful lot of debate on pet forums about this question for some weird reason. But let’s look at the cold hard facts.

There’s no doubt that cats are intelligent. But they lack the cognitive ability to grasp the concept of procreation, or the fact that they’re party responsible for producing kittens.

So its extremely unlikely that they could know when they’ve lost their reproductive capabilities.

With that said, they’ll probably be aware of the scar and may attempt to lick the wound. This is why plastic cones can be so important.

Feline Neutering and Post-Surgery Instructions – Video


Neutering is a humane procedure that can protect a cat from health problems as well as its own urges and behaviors.

Should you decide to get your cat fixed, be assured that the changes you’ll observe will most likely be very positive.

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