Why do cats purr? What a purr can and can’t tell you

What a purr is, and how cats do it

A purr is a low rumble made with the mouth closed. It belongs to the quiet sounds cats use for greeting, attention, acknowledgement and approval, alongside the friendly chirrup. Most purring happens during contact with another cat or a person, though cats purr on their own too.

Exactly how cats do it isn’t clear. It has been suggested that muscles in the voice box, the larynx, twitch rapidly, widening and narrowing the gap between the vocal cords, so the air vibrates as the cat breathes in and out.

It starts in the nest

Kittens can purr almost from birth, mostly while suckling, to tell their mother where they are and that all is well. She purrs too: returning to the nest, she signals quietly that everything is fine without drawing the attention of predators, and the kittens suckle and purr at the same time.

Adult purring stems from these early days, and so does kneading, which kittens use to help the milk flow. Some adult cats still knead a soft blanket or a lap, purring and even drooling as they do. That is not generally a problem.

The contented purr

Most of the time, a purr goes with a content, relaxed cat. Relaxed ears and whiskers, small pupils and a tail pointing up or curled around them mean the purr is most likely a happy one, and perhaps a request for a little attention: a gentle fuss is a good reply.

Cats purr with each other too. Between cats who get on, purring is used as a greeting and often while they groom each other.

The purr that asks for something

Some purrs are requests. Researchers have identified a ‘solicitation purr’ that cats may use when they want food or attention. It sounds more urgent than an ordinary purr, with a high, cry-like note mixed in, and it is hard to ignore.

Listen for it just before mealtimes or when you reach for the treats. A cat who wants something may fix their attention on you, weave round your legs, rub against you or reach up with their front paws, meowing louder and purring higher and more urgently.

Why some cats purr, then bite

A loud purr while you stroke or play with your cat is a sign they are stimulated, and it may come with kneading, drooling and licking. That is fine until it tips over: an overstimulated cat may suddenly grab, bite or scratch, and some purr right up to that moment.

So watch the cat, not the purr. Widening pupils, a lashing tail, ears moving back and a tensing body often come first; stop stroking when you see them. If you are bitten, don’t punish your cat: stay calm, walk away and let them settle. If it keeps happening, offer several short bursts of play or fuss through the day instead of one long session.

Purring when stressed

Cats also purr when stressed. A purr with ears flat or turned to the side, wide eyes and large pupils, and whiskers pointing forwards or down most likely comes from a stressed cat; at the vet, or amid noise and activity, that is probably why. Purring may help a cat soothe themselves, but it doesn’t mean the moment is fine: where you can, reduce or remove whatever is causing the stress.

Purring when unwell or in pain

Cats purr when sick or injured too, and some purr when in pain. Cats with long-lasting pain or illness can sometimes hide their discomfort for a long time, so never let a purr reassure you on its own.

A pain purr may sound faster than the slow, rhythmic purr of a content cat, but the two can sound almost the same, so judge by body language, behaviour and the situation. Nobody knows for certain why a hurting cat purrs: it may be self-soothing, and a sick cat’s purr has a different frequency from a healthy one.

Pregnancy, birth and heat

Hormones play a part too. A pregnant cat may purr more and seek you out more than usual; just before giving birth she may purr and pant, grow restless and look for a quiet, warm nest, and some cats purr while giving birth. If anything about the birth worries you, call your vet. A female cat in heat typically becomes more affectionate, rubs against you more, rolls on the floor, purrs and meows a lot.

When to call the vet

Talk to your vet if your cat purrs a lot more than usual or in new situations, or if a cat who always purred suddenly stops, or one who never did suddenly starts. Look for signs of pain alongside: hiding more than usual, sleeping more, eating or drinking less, a hunched crouch with squinting eyes, reluctance to jump down, crying out when moving or using the litter tray, or less tolerance of people.

Some things can’t wait. Call your vet if your cat hasn’t eaten for more than 24 hours. If your cat seems to struggle for breath, breathing fast or panting noisily with an open mouth, get them to a vet straight away, purring or not.

A purr is one clue, not the whole answer

Before deciding what a purr means, look at the ears, eyes, whiskers, tail and posture, notice what has just happened, and compare it with what is normal for your cat. The same goes for training: after every session Lapka asks whether your cat stayed relaxed, and a purr alone doesn’t answer that. The whole cat does.