Why Cats Fight With Other Cats and How To Help

Hannah Hart, DVM
By Hannah Hart, DVM on Apr. 27, 2023
two cats on a cat tree fighting

Having cats that fight with each other in a multi-pet household can be stressful. This is especially true if you’ve just adopted one cat and had hoped that your resident cat would be happy to have another cat around.

If the introductions are not going as planned, here’s some insight on what’s behind the cat-to-cat aggression and some things you can try to keep the peace.

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Play Aggression

One scenario where cats may fight with each other relates to play aggression. A cat may be predisposed to play aggression when interacting with another cat if they:

  • Were under-socialized as a kitten

  • Do not get enough playtime and exercise during the day

  • Have not been given appropriate alternative outlets for playing

This can cause injuries if the aggressive cat is overly intense in stalking, pouncing, and biting the other cat during play. While play aggression is more common in kittens, it can happen in cats under 2 years of age that have never had other feline playmates.

Play and grooming between cats is healthy, but it’s important to understand the difference between appropriate play behavior and fighting or dominance behaviors.

Look for ears pointed forward in interest, loose and easygoing body movements, gentle mouthing and rubbing against each other, taking turns with dominant and submissive postures or grooming behaviors, and taking small breaks from playing or grooming. 

A cat on the verge of fighting with their playmate may start to thrash their tail from side to side, flatten their ears, puff up their fur, or have dilated pupils.

Fear Aggression

Another scenario that might cause cats to fight would be fear aggression. An example would be when a cat encounters an unfamiliar cat in their environment without having a proper introduction period.

Fear aggression can also happen when an outgoing cat approaches a naturally shy, fearful cat, or when a dominant cat tries to bully a more submissive cat. In these cases, the shy, submissive cat may lash out at the friendly or dominant cat.

A fearful cat may also avoid the other cat or assume a defensive position by freezing and crouching low to the ground before initiating a more offensive response. When overly threatened, the fearful cat may thrust their ears forward and lunge at the other cat, initiating a fight.

Territorial Aggression

Cats may also fight over their territory, combining territorial aggression, status-induced aggression, and inter-cat aggression. Territory fights can happen soon after new cats are introduced to one another, or they may begin over time as antagonistic feelings build between the two cats and a social order is established and challenged.

It’s not uncommon for cats to claim domains for themselves and protect valuable resources, such as high perching spots, litter boxes, toys, attention from humans, and food and water sources. For instance, if there is only one good spot for the cats to watch birds and other prey animals outdoors, the cats may fight over this prized spot.

Redirected Aggression

Two cats in a household may fight if their aggression is redirected from sensing an unfamiliar cat in the area or hearing a loud noise in the distance. In this scenario, the cats are unable to respond directly to the unfamiliar cat or the frightening noise and may become agitated. This can cause the cats to release their tension on each other, resulting in a fight.

How to Stop Cat Fights

To stop cats from fighting, you’ll want to redirect their attention. You can do this with a short, sudden noise, such as hissing from a can of compressed air (not directed at the cats). You could also redirect play behavior toward an appropriate toy, such as a wand toy.

You should never use physical punishment, yelling, or loud, sustained noises because these can increase fear, anxiety, and aggressive behaviors in cats. You also don’t want to put your hand or any other part of your body between cats that are fighting or try to pull them apart, because you can get injured.

How to Help Cats Get Along

Fighting in cats can be managed with calming products such as multi-cat Feliway diffusers that plug into the wall. Aggressive cats may also benefit from anti-anxiety medications such as fluoxetine and gabapentin, particularly if one of the cats is often the instigator of the fighting.

To resolve fighting between cats long-term, you’ll also need to address the root cause of the behavior.

Play Aggression

For example, play fighting behaviors can be corrected by directing the aggressive impulses toward a more appropriate outlet. Offer your cats a variety of toys with different textures—small, light, catnip-laced toys; balls with bells in them; wand toys; laser lights; and toys stuffed with food or treats are all good choices. Cats may also benefit from more play during the day to help them use energy and keep them mentally stimulated.

Territorial Aggression and Fear Aggression

Territorial, inter-cat, and status-induced aggression can be managed by giving each cat their own space and ample resources, such as multiple cat trees, plenty of toys and attention, and distinct food and water sources, as well as litter boxes spaced far enough away to avoid squabbles.

Cats with personality differences or those that were introduced too quickly without the proper setup may benefit from a reintroduction protocol. Here are some steps to follow:

  1. Separate the cats into their own confined spaces with food, water, a litter box, a perch, toys, and a view of the outdoors.

  2. The cats can then swap spaces and spend a bit of time in each other’s rooms alone.

  3. Slowly, over several days or weeks, the cats may spend increasing amounts of time in each other’s presence, first in crates so they can see and smell each other but not interact, and then roaming freely if fighting and aggressive behaviors do not happen. Attention and praise should only be given to cats when they are calm.

It’s important to have realistic goals when dealing with this situation. With some cats, your goal may have to be peaceful co-existence rather than becoming friends. If you can get cats where they are not fighting with one another, which may mean they ignore each other with even a few hisses here and there, this is achieving the goal. You want the fearful cat to become confident enough to claim their own territory, including their food, water, litter box, and cat tree, and have the dominant one leave the fearful one alone.

Hormonal Aggression

If aggression is due to hormonal influences, male or female cats may need to be neutered or spayed if they are not already.

Redirected Aggression

Cats with redirected aggression issues can be managed by removing the threat from view, such as pulling blinds over windows if the cats act aggressively when they see unfamiliar cats or other animals outside.

Featured Image: iStock/w-ings

Hannah Hart, DVM


Hannah Hart, DVM


Dr. Hart graduated from veterinary school in 2017 and began her career with USDA Food Safety and Inspection Service as a public health...

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