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Why do cats purr?

Date created: 17 11 2017

That velvety purr is music to our ears. More often than not, it’s our buddy’s way of telling us that they’re happy and everything’s okay. But is a purring cat always a happy cat? The reasons for purring aren’t always as simple as they seem...

That purr: where does it come from?
A cat’s purr is caused by the diaphragm pushing air up and out of the chest cavity. On its way out, that air makes contact with the tiny bones and rapidly moving muscles of the larynx. So basically, the purr is the result of air hitting the vibrating voice box.

It’s only the smaller members of the wider cat family who do this. According to the US Wildcat Sanctuary, “happy lions might purr if they could, but they can’t”. Big cats have a layer of cartilage at the back of the throat - and it’s this cartilage that gives them their full-throated roar. So it seems that if you can roar, you can’t purr - and vice versa.


Letting mum know everything’s ok
With a litter of six or more, mum’s got her work cut out when it comes to keeping track of everyone. The new arrivals can’t hear yet; but they can feel vibrations - so purring helps guide the little ones towards where they need to be for their first meal.

Kittens themselves can be heard purring from a couple of days old. It’s thought that this is a way of letting their mother know that they’re happy, healthy and getting enough milk - and as a way of communicating with their siblings.

And as a way of communicating, purring is a lot more discreet than meowing. So for a nursing mother and kittens, it’s less likely to draw the attention of potential predators. Not an issue in your living room - but something that probably came in very handy for your buddy’s ancestors.    

A purring cat is (usually) a happy cat...
Stretched out on your lap, all fours in the air, tummy ready to be stroked… it’s safe to assume that the purring is a sign that your buddy’s happy and relaxed. For the most part, purring is a strong signal of feline contentment . That said, to tell for sure whether your cat is happy, it’s worth reading that purr in context.

Half-closed or slow-blinking eyes, an arched back, ears that stand straight up, gentle rubbing or head butting, a tail held high in the air (but not bristling with anger!): these are all signs of a happy cat. So if you hear purring while any or all of this is happening, your buddy’s definitely having a good day.

But sometimes, it’s a little more complicated…
As you’ve probably noticed, cats can get a little precious about who’s on their patch. If your buddy starts purring when they come across a newcomer it’s a positive sign. They’re not exactly saying that they’re happy to meet the new arrival, but it is a sign of non-aggression.

Cats don’t attack when they’re purring; something that the other cat is likely to be instinctively aware of. So by purring at a newcomer, it can be a way of saying, “I’m number one around here, but I’m not looking for any trouble”. Exactly what you want to hear.

Vets report that purring is common among the felines they see for treatment and consultations. Now, no-one really enjoys a trip to the surgery. So if a cat is purring when they’re in strange surroundings or in a potentially stressful situation, it’s probably one of two things: they’re either trying to comfort themselves - or they’re looking for some reassurance from you.

At the same time, it’s not unusual for cats who are feeling under the weather to purr to themselves. Why do they do it? Again, there’s probably an element of self-comfort involved. It’s also thought that there could be a good evolutionary reason for it; even if they are feeling a bit stressed out, by vocalising, they’re saying to nearby rivals, predators and scavengers, “I’m actually fine, so don’t even think about messing with me!”.

Are you purring at me?
Whether it’s playtime or dinnertime, your buddy’s will probably issue instructions as a meow rather than purr. Probably because it’s more direct - and gets the message across faster.

For the most part, purring is different. It’s their way of expressing how they’re feeling rather than telling you what they want. Interpreting it means looking at it in context - seeing what else is going on to understand how your buddy is feeling.