Why it happens
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Play, not a fight
Playing cats take turns chasing and hiding, swap roles, keep their claws in and make almost no sound, then rest side by side. A real fight looks different: hissing, growling, fur on end, ears flattened and one cat running off to hide.
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Competing for resources
If there is one bowl, one litter box or one favourite spot for everyone, the bolder cat may guard it while the other avoids it or waits. Quiet pressure, when one cat blocks another's way or stares it down, is conflict too.
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A new animal in the home
Cats are territorial and accept a strange cat slowly. A new cat let straight into the shared home is one of the main reasons long-running disputes begin.
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Redirected aggression
A cat wound up by a strange cat outside the window or frightened by a noise may attack whichever housemate is nearest. After such an episode the cats may avoid each other or keep squabbling for days.
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A strange smell
A cat coming back from the vet's or a cattery smells unfamiliar, so the other cat no longer recognises it and starts hissing or attacking.
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Growing up
As kittens grow up, their relationship changes: what used to be play can turn into competition for space. Unneutered toms are especially keen to defend territory; discuss neutering or spaying with your vet.
What helps
- One more than the number of cats Have one more bowl, water dish, litter box and resting place than you have cats, set out in different places rather than in a row. Then no cat has to walk past another to eat or go to the toilet.
- Height and hiding places Cat trees, shelves and beds at different heights let cats share the space without bumping into each other. Every cat needs a place it can retreat to where nobody chases it.
- Introduce a new cat slowly Settle the new cat in a separate room first. Swap beds or blankets so the cats get used to each other's smell, feed them on either side of a closed door, then let them see each other through a baby gate, and only after that allow short meetings while you supervise. It can take several weeks.
- Break up a fight safely Never separate fighting cats with your hands. Clap loudly or slide a cushion or a sheet of cardboard between them, then let them calm down in separate rooms. Do not punish either cat: punishment only raises the tension.
- Tire out the energetic one If one cat keeps chasing another that does not want to play, give the chaser several sessions a day with a wand toy or another hunting toy. A tired, contented cat goes looking for less trouble with its housemate.
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When to see a trainer or behaviourist
If the cats fight in earnest, injure each other, one of them hides all the time or stops going to its food or litter box, or the conflict goes on for weeks, contact a qualified animal behaviourist. Until then keep the cats apart, punish neither and do not leave them to 'sort it out' themselves.
When it is a question for a vet
See a vet if a cat is bleeding, limping or develops a swelling after a fight: bite wounds look tiny at first but can turn into an abscess a few days later. Also see a vet if cats that used to live peacefully suddenly start fighting, or one of them becomes irritable and aggressive, especially an older cat: pain or illness can change behaviour.