Why do cats purr ?

http://www.telegraph.co.uk/et?ac=004582369062218&rtmo=fsw0rlMs&atmo=rrrrrrrq&pg=/et/01/3/18/wcat18.html Gives a report that cats’s purring is to help bone reconstruction. This may be as it may be.

My personal experience is that a cat purrs, not when it is happy, but when it uncomfortable in it’s present situation. There is a definite element of hostility about a purr, for instance the purr when a cat is involutarily placed on your lap that only ceases when the cat is left to it’s own devices.

I think purring is a social ‘I am not happy’ signal and it has nothing to do with a contented cat. I also think any relation to a healing process is pretty far fetched considering the relative energies to say ultrasound with a typical purr.

I don’t know. Occasionally when I’m playing videogames, my cat will hop up on my lap and start to purr. That would hardly seem uncomfortable as she could get off my lap any time she wanted to.

Perhaps she is uncomfortable about you not paying attention to her? Or your movements are disturbing her? You are after all the handiest centrally heated cushion around. Moving is not part of the customer expectation.

With my cats purring has always been in direct proportion to their being happy.

My cat book says that cats will also purr if they are injured or uncomfortable in other ways.Perhaps it is a comfort thing ,IE trying to banish the nasty outside world.

I think the last response by David is closer to the truth. I wish I could find the cite for this, but I recall reading a veterinary study stating that cats tend to purr as a self-comforting mechanism (whatever physiological benefits it may have). One of my cats, for instance, often jumps up and lies on my chest while I am in bed, and begins purring. They all purr when they are being petted. But cats will also purr when they are sick or injured, even when they are not in the presence of people or other animals.

Cats will purr when everything’s purrfect.

Scientists from the Fauna Communications Research Institute in North Carolina have discovered that cat purring is a “natural healing mechanism”. “Wounded cats - wild and domestic - purr because it helps their bones and organs to heal and grow stronger, say researchers”. “Exposure to similar sound frequencies is known to improve bone density in humans.” “Purring had to be advantageous to a cat to survive natural selection, but there seemed to be no obvious advantage for a cat merely to display contentment.” The research team is going to continue to examine whether there can be some way to use the study results to halt osteoporosis and even renew bone growth in post-menopausal women.

For the same reason people hum – they don’t know the words. :slight_smile:

Say, Al, you wouldn’t have a URL ref handy, eh? My ABS (Automatic Bullshit Detector) just went off, so I have to ask.

I can see it now. 50-ish woman goes to doctor:

“Doc, my bones are getting brittle.”

“You’re just gonna have to purr a little more, Ma’m.”

Never mind, Al, I forgot the Internet had search engines.:rolleyes: This is the site you are referring to, I believe:

http://www.animalvoice.com/news.htm#why do cats purr?

Their home page at http://www.animalvoice.com/ includes these lines:

(italics & bold are theirs)

I am not a biologist or zoologist (I don’t even play one on TV) – so if someone more qualified wishes to step in, please do so – but these statements seem more like wishful thinking than proven scientific facts. The rest of the Fauna site has a “flavor” of unsubstantiated pseudo-science claims, which makes me suspicious. I think further investigation into this matter is required before we add Purring 101 to the medical school coursebook.

The waveform analysis of a cat’s purr sure is interesting, tho:

http://www.animalvoice.com/catpurr.htm

A link to Cecil’s column on this topic would be appropriate here:

My sample group of two cats is, admittedly, a little lacking for scientific purposes, but I’ll share my observations anyway:

I have never known either of my cats to purr under unpleasant circumstances. They purr when they are snuggled up on their favorite blankets, nestled in my bed and drifting off to sleep. They purr when I’m at my computer and they jump on on my lap (covered as it is by a soft, polar fleece blanket) start kneading the fabric and slowly settle down for a little nap. They purr when I’m gently brushing them and they get that almost pre-orgasmic look on their faces where their eyes kind of roll up and that tranlucent, protective lid covers their eyes. In short, they purr when they are content, safe, and warm. All these observations are corroborated by my wife’s childhood experience with three cats.

Now lest you think that my cats live in a near-purrfect cat nirvana, let me tell you when they don’t purr. They don’t purr when I force open their mouths and shove a dropperful of antibiotics halfway down their throats, squeezing out the chalky medicine and near choking them in the process. They don’t purr when I grab the squirt bottle and let lose with it, their scolding for scratching furniture they know better than to scratch. They don’t purr when they go to the vet and have a stranger lock them down and shove multiple needles in them. They may hiss, mewl, cry, scratch, bite, and kick – but they definitely don’t purr.

Now I’ve got a bit of a nit to pick with dear Unca Cece. In the column Musicat linked to, he starts off by saying that cats will purr when frightened or badly hurt (though never in my experience, as detailed above). He then says that science is a little unclear on the exact mechanism for purring as “it’s very difficult to induce a cat to purr while you are examining his hyoid apparatus.” But why should this be? If they purr when upset as he claims, I’d think a forceful examination of their hyoid apparatus should have them purring up a storm…

Long ago I considered this question and came up with a simple reason why cats purr. Remember that lions and tigers (oh, my!) also purr as well. Cece covers a solid chunk of the idea with the “homing signal” part of it mentioned in the SD link. As learned behavior, it is no big leap to imagine why adult cats continue to purr in their later years.

I also think that purring serves as a great communication method out in that nasty natural world where ending up on someone else’s dinner plate is a continuing option.

What better way to tell the others in your pride that you are a happy cat, without announcing it to the jungle at large? A nice soft rumbling purr is just enough to let your immediate companions know that all is well without providing audible rangefinding data to nearby predators. When you consider how tiny cat brains are in general, it also makes sense that these feline nit wits require an easily distinguished signal that is highly differentiated from their tradition meows and yowls of distress.

All of this adds up to purring being an excellent tool to convey contentment.

Add my personal observations to Stark’s from a lifetime of cats. I think a cat purrs when it is happy, and I find it difficult to believe that a cat would purr BECAUSE it was sick.

But I once had a kitten who was purring on my lap one night, but found dead the following morning with no visible signs of foul play. I took the corpse to the vet, who said the cat must have been deathly sick and I just wasn’t aware of it.

“But why would he be purring if he was that sick?”

“You were petting him. He was relatively happy.”

Cats do a lot of things that appear to be one thing, but are in fact something quite different.

A cat will lick you, not because it likes you (much) but to assert dominance over you, much like a mother cat and kittens.

In the same way, rubbing their upper lip and head on you is not specifically friendly, it is marking you with their scent from scent glands near their lip. They are saying ‘I own you’

I have observed that a totally happy cat doesn’t purr. One of my cats would visit me in the garden, stretch out spreadeagled flat on her back and expect a tummy stroke. Never a purr emitted. Take the same cat and pick her up from her cusion and plonk her on your lap and a loud purr would start, ceasing only when she was released and able to jump off.

Your purring kitten is familiar, I have often seen a sick cat purring away furiously, only to become quiet again when they get better.

I’ve also had a lifetime of cats, from the one who slept in my crib from three months on, and a succession of feline companionship since then. I’ve never been without purrs, and always thought that it was indicative of contentment.

More recently, I’ve nursed my 15 year old companion through the highs and damn lows of diabetes. When he is in distress, he purrs in a different manner than the contented lap mode. It’s much louder, and more loose and rough than a happy purr. When I pay attention to him, it subsides into the lower register purr. My guess is that cats simply have different purrs for different states of being. Just like their many varied meows.

Having owned many cats my whole life - I’m talking maybe a dozen cats - I must admit that your observation is completely contrary to mine; all the cats I have ever seen purred when they were obviously comfortable and happy, especially when they were getting attention. Even the ones who were sick only purred when they were being scratched and petted.