How to introduce a new cat to the king of the house

Every house has a king (or a queen). They own the sofa, the sunny windowsill and, technically, you. So when a new cat arrives, your resident cat doesn't see a friend. They see a stranger in their kingdom.

The good news: many cats learn to share a home, and some become inseparable. The secret is boring but it works: go slowly, and let the cats set the pace. Watch the short film above for the two-minute version, then read on for the details.

Why slow is actually the fast way

Cats are naturally solitary animals. Throwing two of them into the same room and hoping for the best is the most common way introductions go wrong, and a bad first meeting can leave tension that lasts for months. A slow, step-by-step introduction gives both cats the best chance of accepting each other.

How long does it take? It depends entirely on the cats. Some settle in days, most need a few weeks, and some need longer. There is no prize for finishing early.

Before the newcomer arrives

Health first. At Mumcat, every new cat goes through a quarantine period and a vet check before meeting the others: tests for FIV and FeLV, deworming and vaccines. Ask your vet what your new cat needs before any introductions start.

Prepare a room of their own. Choose a room your resident cat doesn't use much and set it up with:

• food and water
• comfortable beds
• hiding places (a cardboard box counts, and cats love it)
• a litter box
• toys and a scratching post

Use new items or the newcomer's own things, not your resident cat's. Your new cat would smell another cat everywhere, and your resident cat would lose a litter box or a favourite bed, which is a bad start for both. Some people also find plug-in feline pheromone diffusers helpful in this phase.

Step 1: A room of their own

Let the newcomer settle in their room first. Keep the door closed and visit often, quietly, without forcing contact.

Your new cat is settling in when they:

• greet you when you come in (rubbing, chirping, purring)
• rest on their side or roll over, belly showing
• play with toys
• rub their face on furniture and corners
• eat, drink, use the litter box and groom normally

This usually takes from several days to a week or two. If your cat is clearly frustrated (scratching at the door, pacing, meowing for long stretches), give them a bit more space if you can, or move on to the next steps sooner.

Step 2: Smell before sight

Cats recognise their group by smell, so the aim is to create a shared scent before they ever see each other.

• Swap a blanket. Put a blanket the newcomer has slept on in your resident cat's area, and the other way round. Make sure each cat still has plenty of their own beds.
• Watch the reaction. Sniffing, then ignoring it, is great. Avoiding the blanket or hissing at it means you should slow right down.
• Swap spaces. Once both are relaxed with the scent, let the newcomer explore the rest of the house for a while (with your resident cat briefly in another room), and let your resident cat explore the newcomer's room.

Step 3: Meals near the door, or not?

This is where the advice differs, so here is the honest version.

Many shelters feed both cats on either side of the closed door, moving the bowls a little closer each day, so the other cat's smell becomes linked with something good. It is what you see in our film.

International Cat Care's current advice is the opposite: don't use food or play to distract or reward cats during introductions, because cats naturally prefer to eat alone and eating near a stranger can stress them.

Our take: meals must always stay relaxed. If you try the door method, keep the bowls far enough apart that both cats eat normally, and only move closer if they stay calm. If either cat eats less, rushes their food or stares at the door, move the bowls away and feed them apart. No cat should have to choose between dinner and feeling safe.

Step 4: Short peeks

When both cats are relaxed with each other's scent, let them see each other through a barrier:

• a door open a crack (with a door stop so it can't swing open)
• a baby gate or stair gate
• a mesh screen

Relaxed cats glance at each other and carry on with their day. Staring, a tense body, flattened or rotating ears, growling or hissing mean it's time to stop. Calmly call the cat away to another room. Never punish a cat for hissing: it only makes them more afraid.

Keep these sessions short, a few minutes at most at first, and always end on a calm note. If you have more than one resident cat, introduce them one at a time.

Step 5: Together, then enough for everyone

Once both cats are comfortable seeing each other, open the barrier while they are busy doing something else. Don't carry one cat to the other, and don't force them to interact. The goal is simply that they can be in the same room without stress.

Start with supervised time together, then short periods of free time, keeping the newcomer in their room in between. Increase the time gradually.

Then make sure nobody has to fight for the throne. Every cat should have their own:

• food and water bowls
• beds and resting spots
• litter boxes
• scratching areas

A common rule is one of each per cat, plus one extra, spread around the home so no cat can block another. Shelves, cat trees and high perches help a lot, because cats feel safer when they can watch from above.

Hissing? Go back one step

Hissing is not failure. It is feedback. If a session goes badly, return to the last step that went well and stay there longer. Going back is part of the method, not a sign that it isn't working.

When it doesn't work, and that's okay

Some cats simply don't want to share their home with another cat, however carefully you introduce them. That isn't your fault or theirs.

We learned this with Penny. She turned up in our village in 2023 with an injured eye, and she was an absolute sweetheart with people: no hiding, no hissing, just cuddles. But no matter how patiently we tried, living with other cats never worked for her. Today she is in a foster home in Barcelona with several humans and no other cats, which is exactly what she needs. Some cats are happiest as the only royal.

If you're struggling, or things break down after a good start, talk to your vet. They can check for pain or illness behind the tension and may recommend a qualified cat behaviourist.

A Mumcat story that did work: Mikka and Noemi

Mikka was first spotted on the street at the end of October, and it took four months of patience before she finally came out of her comfort zone. Once she was with us, she did her quarantine, tested negative for FIV and FeLV and was neutered before meeting anyone. Today her favourite friend is Noemi. They must be close in age, and they are best pals, very crazy girls at times.

Slow worked. It usually does.