Why do cats purr?

Last Updated WED 28 AUG 2019

This article is written by Pet Circle Veterinarian, Dr Carla Paszkowski BVSc.

Nothing beats curling up with your kitty after a long day and listening to their low rumbling purr as you scratch their head. It is well known that purring is a sign of happiness or relaxation in cats and usually a good indicator that they like you. However this behaviour has also been observed in cats that are in stressful situations, like being in the vet's office, or when they are in pain. So why do cats purr and how does it actually work?

Skip to a section:

1. How Do Cats Purr?

2. Why Do Cats Purr?

3. The Health Benefits of Purring

4. Further Reading

Dr Carla explains How and Why Cats Purr. View more videos like this on Pet Circle's Youtube Channel.

How do cats purr?

In terms of what you feel, that bubbling massage is the rhythmic vibration of the larynx muscles contracting and relaxing quickly. When contracted, the muscles reduce the amount of air that can flow through the diaphragm and larynx and during inhalation or exhalation we hear the purring noise. Every cat has their own unique purring pattern, volume and frequency. The volume of a purr is comparatively low and designed for close range recognition as opposed to other vocalisations. Though some very special cats still manage a purr as loud as a lawnmower which might not be the best way to wake up on a Sunday morning.

Why do cats purr?

Purring is more a muscular tremor as opposed to voluntary vocalisation. As mentioned, cats purr when they are content, happy and relaxed but this behaviour is also apparent when they are feeding, nursing or hungry.

Kittens first start purring when they are suckling. Because they cannot meow while feeding, they can purr and so use this as a way of communicating with their mother. The mother cat will purr back to her young as encouragement. Some cats retain this behaviour as adults and purr when they are eating, while some cats have a special "I'm hungry" purr. Cats who purr when they're hungry usually emit high pitched cries of a similar decibel to a human infant. Some scientists have described this behaviour as exploitive as it triggers our nurturing instincts to feed them faster.

In addition to this, purring has been observed in cats experiencing stress, injury or fear. It appears to be a coping mechanism cats use to comfort themselves and other injured animals. In a way, purring is the kitty equivalent of a lullaby.

The health benefits of purring

Not only can purring help with our kitties mental state but studies show that it does affect them physically. The tremor caused from purring applies a gentle rhythmic pressure to the bones which actually helps to strengthen them. Just as muscles get stronger when you use them, so do bones.

This discovery has inspired research into human technologies. Loss of muscle mass and bone density is seen in low gravity environments. Manipulating tremor behaviour can be used for astronauts to maintain muscle mass and bone density during space voyages.

There are claims that being near a purring kitty can also be beneficial to humans in relieving stress, reducing blood pressure and stimulating bone or muscle repair. Studies have shown that owning a cat can reduce your risk of a stroke by almost one third.

So next time your kitty decides to lie on your chest and purr loudly in your ear at 2am, maybe just go with it. Cause now you know, it may save you in the long run!

Further Reading

Want to read more? Check out our other articles:

Why Do Cats Knead?

5 Reasons to Adopt An Adult Cat

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