A Cat Doesn't Always Purr Out of Happiness: Vets Explain Why Purring Can Mean Stress, Fear or Pain

Your cat is lying in your lap, purring, and you're relaxed: it must be happy. Sometimes it is. But vets warn that cats also make that familiar "prrr, prrr" when they're frightened, stressed or in pain - on the vet's table, for example, where no cat is happy.

What actually is purring? Vet Ignacio Molina of the AniCura Estoril veterinary hospital explains that it's rhythmic contractions of the muscles of the larynx, which open and close the glottis. The result is a soft, rhythmic and usually continuous vibration that a cat can produce both while breathing in and breathing out.

Vet Bárbara Febrel of the Clinicanimal clinic adds that purring is above all a means of communication. Mother cats use it to keep in contact with their kittens, and kittens start purring when they're still very small. Adult cats purr when they're relaxed - when you stroke them, when they're resting or when they're near people they have a good relationship with - but also when communicating with other cats.

When "prrr" means something else

Some cats purr in situations of fear, stress, discomfort or pain: at the vet's, in an unfamiliar place or when something is bothering them physically. Both specialists suspect that purring may then work as a self-soothing mechanism - the cat is literally comforting itself. But both stress that this is a hypothesis, not a proven fact, and that there's still a lot we don't know about purring.

That's why the sound on its own doesn't say much. What matters is the whole picture, and above all - a change from usual behaviour. Warning signs: the cat hides more than usual, avoids being touched, moves less, changes its eating or sleeping habits, sits hunched up or is sensitive to touch. Body language is worth watching too - posture, ears, eyes.

If a cat is purring but at the same time withdrawing, less active or showing discomfort, vets advise a check-up to rule out a health problem. Cats are masters at hiding pain, and purring, it turns out, can be part of the mask. How many times have we read it as "everything's fine" precisely when it wasn't?