Orange cat hissing

Understanding cat aggression

Find out why your cats are being aggressive and how to help them get along.

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, aggressive cats can be formidable.1

This behavior is usually directed toward other cats, but it can focus on dogs and people too. Cat bites are painful and can become infected, so it’s important to address aggressive behavior ASAP.

Read your cat’s body language

Knowing the signs of aggression — and curtailing them — can prevent a confrontation from turning into a catfight. Crouching or stiffened rear legs, with the rear end raised, and the back sloping downward toward the head, is an indication that aggressive behavior may soon occur. Other signs are a direct stare, constricted pupils, flattened ears, a tail curved around the body and tucked in, hissing, spitting, swatting, and caterwauling.3

Outdoor cats

By nature, cats are territorial. The most common type of aggression occurs between unneutered males.3

If your cat has access to the outdoors and tends to get into scrapes, it’s important to regularly check him for injuries. 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.4

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 makeup. Unchecked aggression is likely to escalate when cats that don’t get along don’t have an escape route. Their sharp teeth and claws can be formidable weapons.

What causes aggression?

There are many reasons cats become hostile to one another. Causes include:


If your cat was raised as an only “child” and has had little or no contact with others of his species, he may object when another cat is introduced to his environment and he senses a threat.5

Feeling territorial

When a stray or roaming cat enters a cat’s turf, it can trigger aggression, and spraying is a possibility. Cats’ hackles may also rise up when they sense that another cat is in their territory.1


Even the most gentle strokes can irritate a cat to the point he bites the person petting him.5 Behaviorists believe that repetitive touching can cause discomfort or create static electricity in a cat’s fur that transmits small shocks.1 This is known as “petting aggression.”


Some medical conditions can spur a cat’s aggression. Arthritis, dental disease, rabies, and hyperthyroidism are among the culprits. So the first step in resolving aggression is to have a thorough veterinary exam.1

Dealing with cat aggression

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

Rule #2: For your own safety, never put yourself between two fighting cats. To stop a catfight:1

  • 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 bottle

Once the fight ends, put the cats in two separate rooms, separate their bowls, add another litter box, and add a vertical perch for refuge. It’s also a good idea to provide a quiet hiding spot for each cat.

If they continue to fight, alternate putting one of them inside a separate room, a dog crate, or another safe spot that separates one cat from the other. (Safe spots should include a water bowl, food, and a litter box). Talk to your veterinarian about the best way to gradually desensitize them from each other.

Rule #3: Spay and neuter cats prior to sexual maturity.1

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.


  1. Aggression in Cats. American Society for the Prevention of Cruelty to Animals.
  2. Carozza, Ellen. (2018) Understanding the Cat.
  3. Territorial Behaviour Of Cats. Four Paws International.
  4. Common Cat Diseases. American Society for the Prevention of Cruelty to Animals.
  5. Palacio J., León-Artozqui M., Pastor-Villalba E., Carrera-Martín F.,García-Belenguer S. (2007). Incidence of and risk factors for cat bites: A first step in prevention and treatment of feline aggression. Sage Journals.

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