How to Introduce a New Cat to Your Cat

Why cats need a slow introduction

Cats are territorial, and a stranger appearing in their home is a real stress. A rushed meeting can set off fighting, hiding, spraying or litter box problems that are much harder to undo than to prevent. A staged introduction lets both cats get used to each other's smell and presence before they have to share space.

The pace is set by whichever cat is more stressed. A young, confident kitten and an easygoing adult may progress in days; two older or more anxious cats can take weeks or even months. Either is normal.

Step 1: A room of their own

Set up a spare bedroom, bathroom or laundry room for the new cat, with a litter box, food, water, a bed, a scratching post, toys and a hiding spot. The resident cat keeps the rest of the home as usual, so their routine changes as little as possible.

Spend time with each cat separately, so the newcomer bonds with you and the resident cat does not feel pushed aside. The cats may sniff or paw under the door, which is fine as long as neither seems upset. If there is a lot of growling at the door, block the gap for a while.

Step 2: Swap scents and spaces

Exchange bedding or a soft cloth rubbed on each cat's cheeks, and leave it where the other cat eats or rests, pairing the new scent with treats. Once both seem relaxed about the smell, swap locations for an hour or two: the resident cat explores the new cat's room while the newcomer explores the house.

Swapping spaces lets each cat investigate the other's scent everywhere without the pressure of meeting. Repeat it several times over a few days. Feline pheromone diffusers or sprays may help some cats feel calmer during this stage.

Step 3: See each other through a barrier

Replace the closed door with a tall baby gate, Humane World suggests at least 36 inches, or a door propped open a few inches with a doorstop. Feed the cats or offer treats and play on either side, starting far back and moving closer over several sessions.

Keep these sessions short, a few minutes at a time, and end them before either cat gets tense. If one cat hisses, growls, stalks or hides, close the door, go back to scent swapping for a while, and try again later from further away.

Step 4: Supervised time together

When both cats eat and play calmly at the gate, open it and let them share a room while you watch. Choose a time when they are naturally distracted, such as mealtime or during play with a wand toy. Reward calm or neutral behavior, and redirect any stalking or pouncing with a toy before it becomes a chase.

Gradually lengthen these sessions over days or weeks. Leave them alone together only after repeated relaxed meetings with no signs of stress, starting with short periods while you are home. Make sure there are enough litter boxes (one per cat plus one), food bowls, water, scratching posts and high perches spread around so they never have to compete.

Signs to slow down, and when to call your vet

An occasional hiss is normal communication. Slow down if you see repeated hissing or growling, a swishing tail, ears flattened or turned sideways, raised fur, crouching or slinking, one cat blocking the other from food or litter, or a cat that hides constantly. Go back to the last step that went well.

Talk to your vet if either cat stops eating, starts urinating or defecating outside the box, grooms excessively, or if real fights break out and cause injuries. Your vet can rule out illness and suggest behavioral support. Ask before giving any calming product. Make sure the new cat has had a health check before introductions, so no infection is passed on.

This page is general information, not veterinary advice, and it cannot replace an examination by the vet who knows your pet.