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Why does it mean when cats purr? It’s more scientific than them just being happy

Chances are, you’ve heard that purring is a sign that a cat is happy. And in many cases, that might be true. Cats often purr during activities they enjoy, like if you’re petting them or if they’re getting ready to take a nap in a nice sunny spot in the house. But purring may have different meanings and causes than just indicating happiness.

Scientists are still working to fully understand this cat behavior, and new theories about the reasons behind purring continue to evolve. So, why do cats purr, and what does your cat’s purr really mean? We might not fully understand this behavior, but the information that we do have can help you better understand your cat.

Happy cat sleeping on a cat sofa
Image used with permission by copyright holder

Are cats really happy when they purr?

We’ve long believed that purring indicates that a cat is happy, and that may be true. Cats often purr when humans are petting them, or when they’re kittens nursing from their mother. Purring is often acknowledged as a sign that a cat is content.

But purring can mean other things. Cats can purr when they’re stressed or nervous, and understanding purring isn’t always straightforward.

According to Scientific American, there may be another meaning behind your cat’s purring. Scientists who have researched purring found that the frequency of a cat’s purr can help improve bone density and even promote healing. Since cats tend to spend large amounts of time resting and sleeping, purring might help stimulate the muscles and bones without requiring the cat to exert large amounts of energy. This would also make sense when you consider that cats may purr when they’re stressed or injured. It might be that your cat is instinctively trying to heal and soothe themself by purring.

Why do cats purr and then bite you?

Cats can purr when they’re stressed, so if your cat is purring and then bites you, you might be misinterpreting what their purring indicates. Carefully watch your cat’s body language for signs about what they’re really feeling when they’re purring. If you notice tension in their face, a tightly curled body, and a flicking tail, they probably don’t want you to pet them.

It’s also possible that, even though your cat initially wanted you to pet them and was purring as a sign of happiness, they’ve decided that they’re done with the attention now. Cats can be quite sensitive, not to mention fickle, and if you were petting your cat in a way that they didn’t appreciate, they might feel like they need to bite you to get their message across.

Can cats control their purring?

Not necessarily. NewScientist reports that purring is an involuntary response. Your cat may not even realize they’re purring, and probably does this behavior naturally in different situations.

Black and white cat lying on a cat bed on a sofa
Image used with permission by copyright holder

Why do cats purr loudly?

Your cat might purr loudly for various reasons. Some cats just naturally purr louder than others, but as your cat gets older, their purr may deepen and get louder. If your cat is truly, deeply happy, they may purr extra enthusiastically and turn up the volume.

The same thing can happen if your cat is deeply stressed or injured. They may purr extra loudly in response as their body tries to soothe itself.

Physical issues also can increase the volume of your cat’s purr. If your cat is overweight, they may purr more loudly. Cats who have a respiratory infection may also purr more loudly — look for further symptoms like a runny nose or watery eyes.

If you notice sudden, distinct changes in how your cat purrs, it’s a good idea to take them to the vet for a checkup. An abrupt change in purr volume, tone, or intensity might indicate a physical issue that you should rule out, just in case.

Purring is a fascinating cat behavior that we’re still trying to fully understand. For now, we know that cats may purr for multiple reasons. They do appear to purr when they’re happy, but they can also purr when they’re stressed or upset, indicating this behavior may also be self-soothing. The best thing you can do to understand why your cat purrs is to carefully watch him and look for other clues. Think about what’s happened just before your cat started purring, like whether something surprised them or whether they’ve settled down for a nap. The more you watch your cat, the more you’ll start to understand them and even gain insight into why they purr when they do.

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Paige Cerulli
Former Digital Trends Contributor
Paige's work has appeared in American Veterinarian, Business Insider, Healthline, and more. When she's not writing, Paige…
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