Slow is the fast way

Cats are territory animals. To your resident cat, the home is a map of smells, safe routes and favourite perches, and a stranger walking in can feel like a break-in. That is why vets and welfare groups all say the same thing: don't let two cats just "sort it out". Introduce them in small steps, and let the cats set the pace.

There is no fixed timetable. International Cat Care describes a settling period of several days to a week or two for the newcomer, and Blue Cross says that some pairs need only a few days while others take several weeks or even months. The American Association of Feline Practitioners says it can take a few days to a few months, sometimes longer. Plan for weeks, and be pleased if it goes faster.

Before the new cat comes home

• Book a vet check. Both cats should be in good health, and a new cat should be checked and tested for contagious diseases first. Ask your vet what is right for your cats. If your resident cat is elderly or unwell, ask the vet whether a second cat is a kind idea at all.
• Prepare a base room that your resident cat doesn't use: a spare room is ideal. Give it food, water, a bed, a litter tray, a scratching post, hiding places and toys, all new or belonging to the newcomer.
• Count the resources. The usual advice is one of everything per cat, plus one extra (litter trays, beds, bowls, scratching spots), spread through the home so nobody has to queue or guard anything.
• Add height and hiding. Shelves, cat trees and boxes give a worried cat a way to get out of sight and to watch from above.

The ladder, rung by rung

These are the usual steps from International Cat Care, Blue Cross and the AAFP. Cats move up one rung only when they look relaxed, and they move back down if things get tense. Try the planner below: pick the rung you are on, then what you are seeing.

Reading the room

Good signs: glancing at each other and looking away, relaxed bodies, sniffing noses, playing, eating calmly near the barrier, and a belly on show when a cat rests. Slow-down signs: hard staring, hissing, growling, ears rotated back, tail flicking, pacing or sustained pawing at the door. Stop-and-ask signs: fighting, hiding for days or toilet accidents. Stress can show up as going to the toilet outside the tray, which is also something a vet should check.

Sources differ on food. International Cat Care suggests not using food or play as a distraction during the see-through-a-barrier step, so the cats learn to be calm on their own. Blue Cross suggests tasty food at a distance to build good feelings. If you use food, start far from the barrier and let the cats decide how close to come.

Rule of thumb: if you are wondering whether it's too soon, it probably is. Go back one rung, wait, and try again.

What to look for in a good set-up

• One of each resource per cat, plus one extra, in different rooms or corners.
• More than one way in and out of every room, so nobody can be cornered.
• High and hidden places for the shyer cat.
• Short, regular play sessions with each cat on its own, plus plenty of quiet attention for your resident cat.

Adopting a second cat

If you are still choosing, a local shelter or rescue is a great place to start. Staff know the cats and can often tell you which ones live happily with others, and they can help you with the introductions too.

Sources

• International Cat Care: Introducing cats
• Blue Cross: Introducing cats
• American Association of Feline Practitioners: Step-by-step guide to introducing a new cat to other cats

This guide is general information, not a diagnosis. If your cats are fighting, not eating, or toileting outside the tray, ask your vet.