How to Introduce a New Cat to Your Existing Cat

Cats are territorial, and a botched introduction can lead to months of tension, or fights. The good news: done slowly and correctly, most cats learn to coexist, and many become firm friends. The golden rule is simple: go far slower than feels necessary. Here’s the method that works.

This is a general behaviour guide. If either cat becomes very stressed (hiding for days, not eating, toileting issues) or aggression is severe, speak to your vet, who can rule out illness and refer you to a behaviourist.

Before they meet: set up separately

• Give the new cat their own room, a safe base with food, water, litter, bed, scratching post and toys, door closed.
• Never just put them in a room together. First impressions are hard to undo.
• Make sure you have plenty of resources for the whole household: the rule is one litter tray, feeding station and bed per cat, plus one spare, spread around so no cat can guard them all.

Step 1: Swap scents

Cats “see” the world through smell, so introductions start nose-first.

• Swap bedding or blankets between the two cats so each gets used to the other’s scent.
• Rub a soft cloth on one cat’s cheeks and place it near the other’s food, and vice versa, pairing the new scent with something good (dinner).
• Do this for several days until neither reacts to the smell.

Step 2: Let them explore each other’s space

• Swap the cats over for short periods, let the new cat explore the house while the resident cat investigates the new cat’s room. No direct contact yet.
• This lets each build a full scent-map of the other without confrontation.

Step 3: See but not touch

• Feed them either side of a closed door, then a baby gate or cracked door, so they associate seeing/smelling each other with the good feeling of eating.
• Keep sessions short and positive, and increase the distance if either hisses or tenses. Always end on a calm note.

Step 4: Supervised meetings

• Only when both are relaxed at the barrier, allow brief, supervised face-to-face time in a neutral, open space with escape routes.
• Keep it short, reward calm behaviour with treats, and separate again before anything sours.
• Gradually extend the time over days or weeks.

Signs it’s going well (and not)

Good: relaxed body language, ignoring each other, eating near each other, mutual grooming or play. Back off if you see: flattened ears, hissing that doesn’t settle, stalking, or one cat constantly hiding. Return to the previous step and slow down.

Helpful extras

• Feline pheromone diffusers can take the edge off the stress for both cats.
• Never punish hissing or swatting, it’s normal communication, and punishment makes things worse.
• Be patient. Some cats accept each other in days; others take weeks or months. Rushing is the single biggest cause of failure.

The bottom line

Introduce cats scent-first, then sight, then supervised contact, and go slower than you think you need to. Provide plenty of separate resources, keep every step positive, and back up whenever there’s tension. Get it right and you’ll turn two wary cats into a peaceful (often affectionate) household.