Introducing Your New Cat to a Resident Cat

Many cat-loving households have more than one cat in their family. Cats can be companions, playmates and enrich each other’s lives. However, introducing a new cat to an existing cat-home will take time and patience. There are many theories about what types, ages, or sexes will do well together, but little evidence to support. Choosing a cat with a similar personality and activity level generally works the best. A good rule of thumb is to choose an opposite gender, younger cat than the resident cat; however, cats are interesting creatures and rarely perform as expected!

Cats have evolved from territorial, solitary ancestors. They do not form “packs” as dogs do. Cats tend to explore, hunt and travel alone. They didn’t live in groups or even pairs, and they did not seek out contact with other cats. Considering this natural behaviour of cats, it isn’t surprising that it can often be difficult to introduce a new cat to an existing cat’s territory, or in this instance, your home.

The most important thing to recognize and accept when introducing a new cat is that you cannot force two cats to like each other. Expecting a fast friendship is a recipe for disaster! There is no way to determine if two cats will be friends, but there are techniques you can use to increase the likelihood that they will be friends, or at the very least tolerate each other. It takes time and effort to integrate a new cat in a household, but with patience it can be done and your cats may just become lifelong pals.


To allow time for the newcomer to adjust to you and her new situation, keep her in a separate room with her own food, water, litter, toys and bedding.

Exchange Smells

Feed your resident pets and your newcomer on either side of the door, so they begin to associate each other’s smell with something enjoyable. Swap each cats bedding, collars, or toys every day so they familiarize themselves with each other’s scents.

Supervised Exploration

Once your new cat is eating regularly and using the litter box, let her have free time in the house while confining your other cat to the newcomer’s room. Slowly introduce your new cat to a room or two a day, over a few days.

Visual Introduction without Physical Contact

Once both cats appear to be adjusting well and there is no hissing or growling at the door (typically after one to two weeks), you may allow the cats to see each other and interact without physical contact.

Barricade the door with a screen or a gate and closely supervise the cats as they meet each other. Keep the sessions short and positive.

Physical Introduction While Supervised

Open the door and leave the cats to physically meet each other. Always ensure these sessions are short and very closely supervised.

Physical Introductions with Limited Supervision

Allow the cats to explore each other and the house, with limited supervision. Always be present to watch for any signs of discord but leave them alone to adjust to each other. Keep sessions short and positive.

Solo Physical Introduction

When you are comfortable with the cat’s behaviour so far, you can gradually leave the home for short periods of time and allow the cats to freely interact. Very slowly increase the time left alone together. Make sure to ensure the new cat still has access to their “safe room” at all times.


  • Cats are more likely to get along if they are happy with their environment.
  • Make sure there are plenty of hiding spaces, as well as perches or levels to allow the cats to retreat and be alone when desired.
  • Place food and litter out in the open so that they can access them without feeling trapped.
  • Ensure each cat has access to their own resources (food and litter) at all times.
  • Have separate food dishes and one litter box per cat, plus one extra.

Signs of Aggression

If either cat displays aggressive behaviour do not discipline them. Discipline will only make them associate a bad experience with the other cat. If it is safe to do so, separate the cats and continue the introduction process, possibly moving back a few steps and progressing more slowly.

If there is a fight, try to distract the animals by throwing a pillow at them or spraying them with a water bottle. Watch for bullying behaviours. A cat may “bully” another by preventing their access to resources to food and litter. Ensure each cat has access to their own spaces and their own resources at all times.