Do all cats purr?
Purring is not only seen in domestic cats. Cats can be divided into those that can purr and those that can roar. These sounds are mutually exclusive due to the structure of the larynx - often known as the voice box.
In smaller cat species, such as cheetahs, cougars, domestic cats, lynxes, ocelots, servals and pumas the voice box is rigid, and capable of producing a purr sound. Big cats - lions, leopards, jaguars and tigers – have a softer structure that is able to produce roars. An exception is the snow leopard, who is incapable of either a purr or a roar!
Why do cats purr?
Most people will tell you that a cat purring means they are happy and content, and whilst this can be true, it’s not the whole story. The jury is still out on exactly why cats purr in different circumstances, but research has uncovered a few reasons that could be behind their infamous soft rumble.
Kittens are not precocial unlike some animals, meaning they are unable to fend for themselves when they are born. For the first two weeks of their lives they are both blind and deaf, but they are able to purr after just a few days.
It is likely that this purring serves as a communication tool between mother and kitten, letting her know they are okay or if they need feeding, and helps to strengthen to social bond between them. It is also thought to be a useful way of quietly communicating their location without alerting predators to their presence.
This early behaviour of purring to acquire food can be something kittens take into adulthood. Domestic cats have been shown to conceal a high-pitched cry within their purr to solicit food from their owners. This cry is thought to mimic the sound of a baby’s cry which triggers the human instinct to care for and nurture helpless offspring.
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Cats also often purr when injured or stressed, and in these instances purring may assist with healing. Cats purr at a low frequency of 25Hz and 50 Hz, which is within the acoustic range used therapeutically for healing bones and fractures as well as wounds and muscle strain.
Purring for the purpose of healing may also be used as a maintenance behaviour and to self-soothe – which would help to explain why cats might purr when they are alone or when they appear to be sleeping. This low-frequency purring has been found to be utilised by not only domestic cats but by servals, bobcats, ocelots, and pumas.
Thankfully, the classic idea that a cat purrs when they are in a positive social situation and feel happy also appears to be true. It’s safe to assume that if your cat is relaxing and enjoying a stroke then they are purring to let you know they are content. Of course, all cats are individuals and some purr far more often than others, and some cats have been said to never purr at all!
Rae Foreman-Worsley is a feline behaviour and welfare specialist for Cats Protection
Main image: Lynx © Guido Frazzini/Getty Images