Basic Pet Care

Understanding Cat Aggression

Understanding Cat Aggression

If your cats are doing more growling and hissing than purring and meowing, you're familiar with the sounds of cat aggression – and your home and pets are not as peaceful as they could be.

"Aggression is the second most common feline behavior problem seen by animal behaviorists," according to the ASPCA. "Although cat aggression is sometimes taken less seriously than dog aggression–perhaps because cats are smaller and don't pursue people to bite them–aggressive cats can be formidable."

This behavior is usually directly toward other cats, but it can focus on dogs and people, too. Cat bites are painful and can easily become infected.

Read Your Cat's Body Language

Knowing the signs of aggression – and curtailing them can prevent a confrontation from turning into to a catfight. Crouching or stiffened rear legs, with the rear end raised and the back sloped downward toward the head is one giveaway. Others are a direct stare, constricted pupils, flattened ears, tail curved around the body and tucked in, hissing, spitting, swatting and caterwauling.

Outdoor Cats

By nature, cats are territorial. If yours lives part‐ or full‐time outdoors and tends to get into scrapes, it's important to regularly check him for injuries (the most common type of aggression occurs between unneutered males). Opponents' teeth can leave puncture wounds, which are prone to infection. Also observe your cat's gait. If he starts limping, he should get medical attention.

For outdoor cats, vaccinations are particularly essential. Many communicable feline diseases are spread through blood and saliva, so a small bite or scratch from a fight can lead to serious complications.

Indoor Cats

Not all cats that live together live in harmony. As with people who spend time in close proximity, there may be conflict. If this is the case, don't expect your cats to hiss and make up. Unchecked aggression is likely to escalate when cats that don't get along don't have an escape. And their sharp teeth and claws can be formidable weapons.

What Causes Aggression?

There are many reasons cats become hostile to one another. These are the most common:


If your cat was raised as an only "child" and has had little or no contact with others of his species, he may loudly object when another cat is introduced to his environment and he senses a threat.


When a stray or roaming cat enters a cat's turf, it can trigger aggression. If one cat is an indoor male and the other an outsider, spraying is a possibility. Cats' hackles may also rise up when they are relocated from one home to another.


Gentle strokes can irritate a cat to the point he bites the person petting him. Behaviorists believe that repetitive touching can cause discomfort or create static electricity in a cat's fur that transmits small shocks.


Some medical conditions can spur a cat's aggression. Arthritis, dental disease and rabies are among the culprits. So the first step in resolving aggression is to have a thorough veterinary exam.

Dealing with Cat Aggression

Rule #1: Don't allow cats to fight it out. Uninterrupted, they'll battle until someone gets hurt.

Rule #2: For your own safety, never put yourself between two fighting cats.
To stop a catfight:

  • Clap your hands loudly
  • Toss a soft object near them to distract
  • Bang on a pan or other metal object
  • Spray them with a water gun

Once the fight ends, separate their bowls, add another litter box and a vertical perch for refuge.

If they continue to fight, alternate putting one of them inside a dog crate (include water bowl, food and a litter box). Allow them to be together supervised when they calm down.

Rule #3: Neuter male cats as soon as they reach sexual maturity.

With patience and luck, your two sparring partners will learn to co-exist. So enjoy them, be generous with treats and praise the good behavior that follows.

Susan Breslow is the former head of publications for the ASPCA and is the author of the childrens book I Really Want a Dog.