Purring is one of the most familiar animal sounds, and one of the least fully understood. Cats purr when content, but also when giving birth, injured or stressed. Scientists have learned a lot about how cats purr, while why remains partly a mystery.
Key Takeaways
- Purring is produced by rapid twitching of muscles in the larynx as the cat breathes in and out.
- Typical purr frequencies fall roughly between 25 and 150 hertz.
- Cats purr in many situations, including contentment, stress and pain, suggesting the sound has several purposes.
- Some researchers have suggested purr frequencies could aid healing, but this is not proven.
How cats purr
The long-standing explanation is that signals from the brain make the laryngeal muscles twitch many times a second, causing the vocal folds to separate and close. Air passing through as the cat breathes in and out produces a continuous vibrating sound.
A 2023 study published in Current Biology found that vocal folds in cat larynges could produce purr-like low frequencies even without active muscle contraction, possibly because of pads of tissue in the folds. Scientists still debate how these mechanisms combine.
Why cats purr
Contentment and social signals
Kittens begin purring within days of birth, and mothers purr while nursing. Purring may help mother and kittens communicate and bond. Adult cats often purr when petted or relaxed.
Asking for something
Research has found that some cats produce a “solicitation purr” when asking for food, with a high-pitched component similar to a cry. People in studies rated these purrs as more urgent.
Stress and pain
Cats also purr at the vet, when injured or when giving birth. One idea is that purring is a self-soothing behaviour. This is a reason not to assume a purring cat is always comfortable.
The healing hypothesis
Some researchers have suggested that low-frequency vibrations around the range of purring could encourage bone and tissue repair, based on studies of vibration therapy in other contexts. This is an intriguing hypothesis, but direct evidence that purring helps cats heal is limited.
Do big cats purr?
Smaller cats, such as domestic cats, cheetahs and pumas, purr. Lions, tigers, leopards and jaguars can roar but are generally not considered true purrers, though they make other sounds.
Reading your cat
Look at context and body language along with the purr. A relaxed cat with soft eyes and loose posture is likely content. A cat that is purring while hiding, not eating or breathing unusually may be unwell and should see a vet.
Frequently Asked Questions
Can cats control purring? Cats appear to start and stop purring voluntarily.
Do all cats purr? Most domestic cats do, but volume and frequency vary.
Is purring good for people? Many people find it calming, though claims of health benefits for humans are not well established.
The bottom line
Purring is a flexible signal. It can mean contentment, a request or a cat coping with discomfort, so always read it in context.
