How To Introduce Two Cats When One Is Aggressive?

How To Introduce Two Cats When One Is Aggressive
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Introduce your cats gradually by keeping them in separate rooms for the first couple of days or weeks. Give them their own beds, bowls, and litter boxes. Feed them on opposite sides of a door so they can hear and smell each other. This way they become familiar with the other cat’s presence and associate it with getting fed, which is a good feeling.

After a few days, let them interact with your supervision and teach them that good behavior with the other cat will earn them a treat. Sooner or later, the positive reinforcement will make them calmer in the presence of the other cat.

If you want to know more about how to introduce two cats to each other, keep on reading.

Why is my cat being aggressive?

Before diving into how to introduce your cats, we have to discuss why the cats are being aggressive in the first place.

1. Territorial aggression

This occurs when a cat feels that an intruder has invaded its territory. A cat may be aggressive toward the most passive cat, yet friendly with another. Problems may arise if a new cat is brought home, a kitten reaches maturity, or if your cat encounters a neighborhood cat.

Aggressive behaviors include stalking, chasing, hissing, ambushing, swatting, and preventing access to places.

Female cats can be just as territorial as males.

2. Inter-male aggression

Adult male cats may threaten or fight with other males. This behavior is more common among unneutered cats. They may be fighting over a female, positions of power, or territory.

They will stare, stalk, yowl, and puff up their fur to threaten the other cat. If one cat does back away, the aggressor will usually walk away as well.

If neither backs down, the cats may fight. They may roll around swatting, kicking, biting, or screaming. They might stop suddenly in the middle of a scuffle, posture again, and go back to fighting.

If you see signs that a fight is about to occur, distract both cats by making loud noises, startle them by dropping an object nearby, or spray them both with water. Always keep your distance and never put any body part in the middle of a fight.

3. Defensive aggression

This occurs when a cat tries to defend itself from an animal or human it thinks is trying to harm it. This can occur as a response to a person punishing them, an attack from another cat, or any incident that makes the animal feel threatened or afraid.

Defensive postures by your cat include crouching with the legs and tail pulled in under the body, flattening of the ears against the head, and rolling slightly to the side.

4. Redirected aggression

Cats can direct aggression toward another animal, or even a person, who did not initially provoke the behavior. For example, let’s say your cat sees a cat run across the front yard. It gets agitated because a cat just trespassed on its territory. When you try to pet your cat, they turn around and bite you. This is your cat working solely on impulse. It is so worked up at that point that it is not aware that it is you it is biting.

 Redirected aggression
Image: / Sena Yiğiter

How do I introduce two cats?

1.  Control first impressions.

The first impression a cat makes when it meets a new cat is critical. If both cats display aggression during the first meeting, this may set the mood for their future relationship. It may be best to separate the cats so that you can control their initial meeting.

The two cats should be able to smell and hear, but not see or touch, each other. Each cat should have its own bowls, litter box, and bed. Feed the cats near the door that separates them so they learn that coming together results in a pleasant experience. Feed both cats special treats near the door as well.

After two or three days, switch the cats’ locations so they can investigate the other’s smell. This allows each cat to explore different sections of your home. Some experts suggest rubbing both cats with the same towel separately to intermix their scents.

Play with each of the cats near the door. Encourage them to paw at toys under the door. Eventually, the cats may play “paws” under the door with each other.

2. Let the cats see each other.

After a week with no signs of aggression at the door, introduce the cats to each other.

One method is to replace the door with a temporary screen door. Ask a family member to help you with the process. Set each cat down a few feet away from the screen.

When the cats notice each other, say their names and toss treats to them, aiming behind them. Over the next few days, continue feeding, giving treats, and playing near the barrier, inching closer and closer to the screen.

3. Let the cats spend time together.

Permit the cats to spend time together without a barrier between them. Supervise these initial interactions carefully.

Bring the cats together when they are likely to be relatively calm, such as after a meal or strenuous play. Keep a spray bottle nearby in case the cats begin to fight. As the cats become more familiar with each other, allow them longer and longer periods of time together.

How do I get my cats to like each other?

How do I get my cats to like each other
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  1. Make sure each cat has plenty of its own space. Put their food and water bowls, litter boxes, and beds in separate areas.
  2. Do not give catnip to your cats while in the process of introducing them to each other. Catnip can make some cats aggressive.
  3. Make the time they spend together as pleasant as possible. Encourage fun activities, such as playing and giving each cat a treat.
  4. If you have a big cardboard box, open both ends and put it on the floor for them to crawl and play in. It is rare to find a cat that does not have fun with cardboard boxes.
  5. Give each cat plenty of individual attention.
  6. Do not leave the cats alone together when you go out until you are absolutely sure they are not going to get into a serious fight.
  7. If your cats are not neutered or spayed, they will be more prone to aggressive behavior. If you do not plan on breeding cats, have them fixed.

What should I avoid when introducing two cats?

  • Do not count on cats to work things out on their own. The more they fight, the worse the problem will become. Break up the fight before it even begins.
  • Do not touch either cat when they are being aggressive. You might end up injuring yourself.
  • Do not punish the cats; this could cause further aggression and fearful responses. You may become the target of redirected aggression.
  • Do not add more cats. Some cats are willing to share their house and territory with multiple cats, but the more cats who share the same territory, the more likely it is that some of your cats will not get along with each other.

How long does it take cats to get used to each other?

It takes eight months to a year for cats to develop friendships. Some will learn to love each other, but other times you might have to face the reality that not all cats will get along. They will usually avoid each other if a friendship does not develop but sometimes fights to break out. If the fighting persists, one cat may need to be rehomed.


Cats must be introduced to each other gradually. Put them in different rooms of the house with their own set of bowls, litter boxes, and beds. Then let them hear and smell each other through a door until they start to become familiar and comfortable with each other. Only then should you let them see each other. Supervise all playtime in the beginning until you are sure that they can be left alone together.

Make sure each cat has their own space that only it can access. Give each cat plenty of individual attention. Get your cats spayed and neutered to lessen their propensity for aggression.

Be patient and give the cats eight months to a year to develop a bond. Soon you will have happy cats who have a harmonious relationship.