House cats purrrrring...

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Robert Bodling - 18 Oct 2006 11:55 GMT

Why do cats purr and what causes them to purr? What is the purr sound you
hear from them? Is it the rhythm of their heart, or what?

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Ivor Jones - 18 Oct 2006 12:11 GMT

> Why do cats purr and what causes them to purr? What is
> the purr sound you hear from them? Is it the rhythm of
> their heart, or what?

It's a closely guarded cat secret, only cats know and they won't tell ;-)

Ivor

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krazy - 18 Oct 2006 14:03 GMT

>Why do cats purr and what causes them to purr? What is the purr sound you
>hear from them? Is it the rhythm of their heart, or what?

From http://cats.about.com/cs/catmanagement101/a/why_cats_purr.htm

Why and How do Cats Purr?

My mailbox often brings interesting challenges, as in this morning's
short question from Gideon: "Do cats purr when they are alone?" What a
great question! As I replied to Gideon, it is on the order of, "If a
tree falls in the woods, and there's no one there to hear it, does it
make a sound?" Or - "Does the light burn inside a closed
refrigerator?" Yet, by far, I think the question about cats purring is
the much more fascinating of the three. Truthfully, I don't know if
cats purr when they are alone. It seems likely that they do, if one
understands a little about why cats purr.
Most experienced "cat wranglers" now know that cats don't purr only
when they are content and happy. They also purr during tense or
traumatic moments. When suddenly and violently injured, even at
moments near death, a cat will often purr. I've often likened this to
saying, "Please don't hurt me any more. I'll be good," but recent
studies have put a more scientific spin on this seeming anomaly.

It seems that the measurable Hertz of a cat's purr lies between 25 and
150. Coincidentally (or not) it has been found that sound frequency in
this range can stimilate bone growth and healing. ¹

That cats have remarkable endurance, and are quite stoic to trauma is
well known to veterinary professionals; it is not unlikely that this
instinct to purr under duress is directly related.

Purring under stress has more colorfully been described as the cat's
mantra, e.g., a self-soothing, self-healing, relaxing, vibrating sound
(sort of like the Ommmm one might hum while in the lotus position.
Notice the vibration in your lips, nose and throat? I bet most of us,
if we had our "druthers," would much rather be able to purr!

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Mike - 19 Oct 2006 03:15 GMT

Isis' purr switch is funky. I can't hear her purring. I have to put my
fingers on her throat to feel the vibration.

One thing I do know is that she purrs when she is inhaling, exhaling, or
between breaths. I have to come to the conclusion that the purr engine
functions independently of breathing.

Mike in Illinois

> Why do cats purr and what causes them to purr? What is the purr sound you
> hear from them? Is it the rhythm of their heart, or what?

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Upscale - 19 Oct 2006 03:44 GMT

"Mike" <nospam@dot.com> wrote in message

> Isis' purr switch is funky. I can't hear her purring. I have to put my
> fingers on her throat to feel the vibration.

I can certainly here my Deetoo purring. I like to put my ear to her side
when she's purring to hear how load it is. Makes me laugh every time.

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tension_on_the_wire - 19 Oct 2006 05:22 GMT

> "Mike" <nospam@dot.com> wrote in message
> > Isis' purr switch is funky. I can't hear her purring. I have to put my
> > fingers on her throat to feel the vibration.
>
> I can certainly here my Deetoo purring. I like to put my ear to her side
> when she's purring to hear how load it is. Makes me laugh every time.

Muezza.Glorio has a Steppenwolf purr........
No meow....he squeaks like a mouse when he tries to meow,
but a purr that'll knock your socks off.

--tension

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Mike - 19 Oct 2006 16:25 GMT

I did more investigation last night. For instance, Isis was not purring via
my finger on the throat test. I administered ear scratches and the purr
kicked in strong. It then remained in the 'on' condition for quite a while.

While there does seem to be a very small correlation between purring and
breathing I am sure that the purr machine runs independently of the air
intake and exhaust system.

I have to believe that purring is created by some kind of blood vessel
fluttering or other mysterious mechanism. Maybe it's a modified growling?

Mike in Illinois

>> "Mike" <nospam@dot.com> wrote in message
>> > Isis' purr switch is funky. I can't hear her purring. I have to put my
[quoted text clipped - 8 lines]
>
> --tension

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Upscale - 19 Oct 2006 16:55 GMT

"Mike" <nospam@dot.com> wrote in message

> While there does seem to be a very small correlation between purring and
> breathing I am sure that the purr machine runs independently of the air
> intake and exhaust system.

I don't agree. After you mentioned it, I watched my Deetoo as she was
purring. The high and low volume noises of her purr coincided exactly with
the rise and fall of her chest as she was breathing.

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Mike - 19 Oct 2006 17:38 GMT

Ok, but put your ear right against her side and listen. Does the purring
continue even at the moment when she has completely exhaled? There is a
point where the air flow goes to zero. If purring continues even then then
it operates without air flow, no?

Maybe purring is amplified, as tension suggests, due to air flow. I think
all this purring business is near or in the vocal chords.

I don't know why we can't get a definitive answer on this. Surely a cat
surgeon somewhere knows the real story.

Mike in Illinois

> "Mike" <nospam@dot.com> wrote in message
>>
[quoted text clipped - 5 lines]
> purring. The high and low volume noises of her purr coincided exactly with
> the rise and fall of her chest as she was breathing.

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tension_on_the_wire - 19 Oct 2006 18:08 GMT

> Ok, but put your ear right against her side and listen. Does the purring
> continue even at the moment when she has completely exhaled? There is a
[quoted text clipped - 8 lines]
>
> Mike in Illinois

Well, since it is a dynamic phenomenon, you can't dissect
a purring cat in the hopes of catching him in the act.
Maybe doppler ultrasound ... no it will catch the blood flow,
and even the turbulence, but not the origin of the sound.
It's a puzzle, for sure.

I'm happy enough with the sound...don't need to know where
it comes from.

8^)

--tension

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Mike - 20 Oct 2006 00:49 GMT

> I'm happy enough with the sound...don't need to know where
> it comes from.

Tension,

I'm drawing the line right here. For six years I have lived with
mysteries.

1. Why does she walk around in circles before plopping down in her box
under the office lamp?

2. Why does she lie upside down, look me in the eye, and go meeeooowww.
(This one makes me really crazy).

3. How does she know when to hide behind the door and jump out at me and
catch me completely unawares?

4. What is this knead knead business that goes on? Why does she do it in
the same spot every night just before bed?

5. Why does she bury only canned food with mounds of invisible dirt and
never try to bury dry food?

My life's mission is to solve one cat mystery and purring is going to
be it.

Mike in Illiniois

>> Ok, but put your ear right against her side and listen. Does the purring
>> continue even at the moment when she has completely exhaled? There is a
[quoted text clipped - 22 lines]
>
> --tension

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Ivor Jones - 20 Oct 2006 01:13 GMT

[snip list of mysteries I don't understand either..!]

> My life's mission is to solve one cat mystery and
> purring is going to be it.

You'll never do it, Mike..! People have been baffled for centuries..!

Ivor

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tension_on_the_wire - 20 Oct 2006 04:50 GMT

> > I'm happy enough with the sound...don't need to know where
> > it comes from.
[quoted text clipped - 21 lines]
> My life's mission is to solve one cat mystery and purring is going to
> be it.

Okay, Mike, well...good luck with that!

--tension

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Upscale - 19 Oct 2006 22:47 GMT

"Mike" <nospam@dot.com> wrote in message

> Ok, but put your ear right against her side and listen. Does the purring
> continue even at the moment when she has completely exhaled? There is a
> point where the air flow goes to zero. If purring continues even then then
> it operates without air flow, no?

There's not enough lag time between breaths for me to tell. All I know is
that the purrs are synchronised perfectly with her inhaling and exhaling.
But, as Tension stated, I'm glad it's there and it's certainly one thing
that is most definitely attributed to cats.

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Ivor Jones - 19 Oct 2006 22:57 GMT

> "Mike" <nospam@dot.com> wrote in message
> > Ok, but put your ear right against her side and listen.
[quoted text clipped - 8 lines]
> stated, I'm glad it's there and it's certainly one thing
> that is most definitely attributed to cats.

I just felt my Missy's "purrbox" at the front of her throat, while the
sound is definitely amplified by her breathing, the throb I feel when I
put my finger there is still there even in the pause between breaths. So I
lean towards the theory that it's blood flow amplified by breathing.

Of course as I said before, it's a cat secret and they'll never tell ;-)

As others have said, it's a most pleasant sound, if not *the* most
pleasant, lovely to wake up to with a cat's chin resting on your arm :-)

Ivor

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tension_on_the_wire - 19 Oct 2006 16:57 GMT

> I did more investigation last night. For instance, Isis was not purring via
> my finger on the throat test. I administered ear scratches and the purr
[quoted text clipped - 8 lines]
>
> Mike in Illinois

I've read two theories, that either it is in the vocal cords vibrating,
or in the blood vessels with turbulent blood flow, and that both
ideas could be amplified by the breath.

--tension

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