Veterinarian-written / veterinarian-approved articles for your cat.

Injury or Illness-Related Aggression in Cats

Cats that are sick or hurt may become aggressive to people or pets in the home.

Has your cat suddenly seemed to have a change in personality? Is she attacking you or other animals in the home or keeping to herself and biting if you try to handle her?

There are several reasons for a cat to develop aggressive behaviors toward you or others in your home. One of them is pain. Illness or injury commonly causes cats that were previously peaceful to become defensive or aggressive.

Cats Hide Illness Well

Cats tend to be stoic about their illnesses and injuries, even actively trying to hide them. It can be difficult to determine if your cat is sick or hurting, and it may not occur to you that it could be the cause of a sudden increase in your kitty's aggression.

If your cat is exhibiting any of the following signs concurrently with an increase in biting, attacking, or acting defensively with humans or other pets in your home, illness or injury may be the cause:

  • Withdrawing from social interactions; hiding more.
  • Decreased appetite.
  • Other personality changes such as decrease desire for attention or lack of interest in playing.
  • Decreased grooming resulting in a greasy coat and/or mats.
  • Limping or a hunched up body position.
  • Changes in litter box habits such as urinating outside of the box.
  • Yowling or meowing incessantly.
  • Sneezing, coughing, nasal or ocular discharge.

You can learn more here: "How To Know When Your Cat Is Sick."

Why Do Some Cats Become Aggressive When Ill or Injured?

Cats may become aggressive when they are in pain because they are afraid of having the pain exacerbated. For instance, if they have an ear infection that is causing them pain and you stroke that area, the pain could become worse.

Also, cats don't always understand that pain comes from within them, and they may associate the pain with an outside force. This is common with cats that are experiencing urinary pain. They often begin urinating outside of their litter box because they associate the box with the pain.

What to Do if Your Cat Is Acting Aggressively

If your cat begins showing aggression toward humans or other pets, the first thing to do is visit your veterinarian.

You can learn about other causes of feline aggression in these articles:

"Cat Aggression: Why Some Cats Fight"

"Cat Aggression Overview"

"Play Aggression in Cats"

"Petting Induced Aggression in Cats"

"Human-directed Aggression in Cats"

You May Also Like These Articles:

Human-directed Aggression in Cats

Redirected Aggression in Cats

Why Do Cats Hiss at People?

Cat Aggression: Why Some Cats Fight

Cat Aggression Overview

Play Aggression in Cats

Petting Induced Aggression in Cats

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