How Do Cats Purr?

How do cats purr? Answer: A cat’s purr is very special and very noticeable. It is unique to the cat and the humble domestic cat is better at it than the mighty big cats. Tigers can produce a rather spluttered one way (exhalation) purr but that is it. Domestic cats, as we know, can purr with exhaled and inhaled air, with their mouth shut and do it for a long time sometimes.

So how do cats purr? Well it has to be the air in the cat’s breath passing over a piece of anatomy that constricts and relaxes rapidly. The Cat Owner’s Home Veterinary Handbook by Drs Carlson and Giffin explain it like this. When a cat breathes in and out the cat alternately tenses and relaxes the muscles of the voice box and diaphragm. The diaphragm is a sheet of muscle that extends across the cat’s body at the base of the lungs. It separates the thoracic cavity (the space containing the lungs) from the abdominal cavity (the space where the stomach and viscera is).

This relaxing and tensing of these muscles results in turbulent air flowing through the trachea. The trachea is a tube running from the larynx (which is below the back of the throat) to the lungs. These rapid cyclical changes in air pressure are “superimposed” on normal breathing to produce the characteristic purring.

Purring is entirely instinctive and a kitten will purr from 2 days old. Purring does not always indicate that the cat is content. Cat purring can happen when the cat is in pain, hungry and/or upset. Cats have been known to purr just before dying.

Some more (overlap): Cat Purr.


  • As stated in the text and:
  • Wikipedia (anatomy)
  • Cat Watching by Desmond Morris

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