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Aggression Between Cats

Are your cats suddenly fighting or behaving aggressively? Did you bring a new kitten home who isn’t getting a warm welcome from your resident cat? 
It’s important to identify what is triggering your cat’s reaction so you can help reduce the conflict and ensure your feline friends can comfortably coexist in their home.

It is impossible to predict how well a pair or group of cats will ultimately get along. Some cats are especially territorial and may never be able to share their home, while others do well in a multi-cat household. There are several reasons why cats might not get along, but the factors that determine how well cats will get along are not fully understood. In fact, even cats who have gotten along in the past can begin to develop problems with each other.

Types of Aggression Between Cats

Territorial Aggression

One of the most common reasons why cats may not get along is under-socialization. If your cat grew up with little to no contact with other felines, they may react strongly when introduced to another cat. Cats are a territorial species and problems may occur when a new cat is brought into a household, when a young kitten reaches maturity, or when house cats encounter outdoor cats. It is not uncommon for a cat to be territorially aggressive toward one cat in a family, but friendly or tolerant of another one. 

Typical territorial behavior can include stalking, chasing, ambushing, hissing, howling, yowling, swatting, and preventing the other cat from having access to certain spaces.

Inter-male Aggression

Inter-male aggression is mostly common in adult males who have not been neutered. They tend to threaten and/or fight with other males to challenge them over females, or to achieve a higher position in their social hierarchy. 

Typical inter-male aggressive behavior can include stalking, staring, yowling, howling, and puffing up their fur to threaten each other. If one cat walks away, the brawl never starts, but if no one backs down, the cats may fight. 

Defensive Aggression

Defensive aggression occurs when a cat feels threatened or afraid. 

Typical defensive behavior can include crouching with their legs pulled under their body, lying down with their ears back and flat to their head, tucking their tail, or rolling slightly to the side. If a cat continues to approach another cat who is in this posture, a fight will likely occur.

Redirected Aggression

Redirected aggression occurs toward another animal who didn’t initially provoke the behavior. This can appear suddenly between cats who have gotten along previously and is usually caused by some sort of threatening trigger, like a passing dog, a garbage truck driving by, or an unexpected sound in the home. A common example: they may see a stray cat walk past their window causing them to react, but since there is a barrier between them and the outdoor cat, your pet may lash out at other animals – or even people – inside the home. When something startles both cats, they see one another reacting and both can become defensive. 

How to help your cats get along

Since cats have a somewhat flexible social hierarchy, there are things you can do to help re-kindle their relationship or set new pairings up for success. 

What you can do:

  • Spay and neuter the pets in your home, even if one cat is unaltered it can play a role in the overall behavior of the group.
  • Separate their resources so that they are not concentrated in one part of the home. Rather than having their litter boxes, food, water, toys, and climbers all in one room, do your best to scatter these items throughout the house so there isn’t as much competition for these important resources.
  • Provide additional perches to create more vertical space, as well as hiding spots. Some cats feel most comfortable up high, while others prefer to find places to hide that are low to the ground and more secure. By giving them their preferred escape route, it will reduce their stress level and give them space away from their fellow felines when they need it. It doesn’t need to be an expensive climbing tree or a plush cat condo; get creative with sturdy shelves, strategically placed furniture, or even a blanket folded under a low table. 
  • Prevent future fights. Just like humans, repairing a feline relationship can take some time and effort. If their behavior is excessive or frequent, your cats may need to be temporarily separated while you’re working on these changes.
  • Slowly reintroduce your cats (see our info on Introducing Cats). If the problems continue, you may need to consult your veterinarian or a certified behavior specialist who is familiar with feline behavior.

What not to do:

  • Do not let cats fight it out; the more often cats fight, the worse the problem becomes.
  • Do not punish the cats; punishment is likely to elicit further aggression and fearful responses. This may also make you a target for redirected aggression.
  • Do not touch the cat during an altercation; if cats are showing any signs of aggression towards each other, you should never touch them or try to break up the fight using your body. During a cat fight, you can intervene by tossing something light and soft at them (like a towel, blanket or small pillow), making a loud noise, or squirting them with water. Never try to pull two fighting cats apart.

Important note: If there is a sudden, seemingly unexplained change in your cat’s behavior, consult a veterinarian as your cat may have underlying medical issues.