why do cats purrrrrr?

Question

what does it mean when a cat purrs. what are they trying to say

Answer 1

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!

The Physiology of Purring

There seems to be two schools of thought here.

The most popular one is quoted here:
One study determined that purring involves activation of nerves within the voice box. These nerve signals cause vibration of the vocal cords while the diaphragm serves as a piston pump, pushing air in and out of the vibrating cords, thus creating a musical hum. Veterinarian Neils C. Pederson, author of Feline Husbandry, believes that purring is initiated from within the central nervous system and is a voluntary act. In other words, cats purr only when they want to.²

The other theory is that the sound comes more from vibrating blood vessels than in the voicebox itself. ³
The Happy Purr of a Cat

All domestic cats are born with the purring ability. A queen will purr while giving birth. It is unknown whether this is because of happy anticipation, or whether it is a relaxing "mantra." Kittens instinctively purr when nursing, and the momcat purrs right back at them. Your adult cat will purr at the drop of a hat whenever you're near, and especially when you are holding or petting him.

Cat purrs will range from a deep rumble to a raspy, broken sound, to a high-pitched trill, depending on the physiology and/or the mood of a cat. A cat will often "wind-down" when going to sleep, with a long purring sigh that drops melodically from a high to a low pitch. Does your cat's purr sometimes sound like an idling diesel engine? That's because at the lower range of 26 Hertz, the velocities are nearly the same.

The Healing Power of the Purr

Cats are often used as "therapy animals" in convalescent hospitals, or in retirement residences. It is an accepted fact that cat owners have lower blood pressure, especially in older people. The human-feline bond is never quite so close as when a person is holding and petting a purring, vibrating bundle of fur on her lap, and all is well with the world. You may even find yourself purring in response.

Resources

¹SCIENTIFICAMERICAN.com: Why do cats purr?

² PetPlace.com: Why Do Cats Purr?

Answer 2

No one knows for sure why a domestic cat purrs, but many people interpret the sound as one of contentment. Our understanding of how a domestic cat purrs is becoming more complete; most scientists agree that the larynx (voice box), laryngeal muscles, and a neural oscillator are involved.

Kittens learn how to purr when they are a couple of days old. Veterinarians suggest that this purring tells ‘Mom’ that “I am okay” and that “I am here.” It also indicates a bonding mechanism between kitten and mother.

As the kitten grows into adulthood, purring continues. Many suggest a cat purrs from contentment and pleasure. But a cat also purrs when it is injured and in pain. Dr. Elizabeth Von Muggenthaler has suggested that the purr, with its low frequency vibrations, is a “natural healing mechanism.” Purring may be linked to the strengthening and repairing of bones, relief of pain, and wound healing (See Web link to Felid purr: a healing mechanism).

Purring is a unique vocal feature in the domestic cat. However, other species in the Felidae family also purr: Bobcat, Cheetah, Eurasian Lynx, Puma, and Wild Cat (Complete list in Peters, 2002). Although some big cats like lions exhibit a purr-like sound, studies show that the Patherinae subfamily: Lion, Leopard, Jaguar, Tiger, Snow Leopard, and Clouded Leopard do not exhibit true purring (Peters, 2002).”

What makes the purr distinctive from other cat vocalizations is that it is produced during the entire respiratory cycle (inhaling and exhaling). Other vocalizations such as the “meow” are limited to the expiration of the breath.

It was once thought that the purr was produced from blood surging through the inferior vena cava, but as research continues it seems that the intrinsic (internal) laryngeal muscles are the likely source for the purr. Moreover, there is an absence of purring in a cat with laryngeal paralysis. The laryngeal muscles are responsible for the opening and closing of the glottis (space between the vocal chords), which results in a separation of the vocal chords, and thus the purr sound. Studies have shown, that the movement of the laryngeal muscles is signaled from a unique “neural oscillator” (Frazer-Sisson, Rice, and Peters, 1991 & Remmers and Gautier, 1972) in the cat’s brain.

Answer 3

Why Cats Purr

Ever wonder why a cat starts purring when you pet it? Or why some cats will start purring before you even pet it? It's not just because the cat is happy. Your cat might even purr when he's dying.
The older a cat gets, the more its purr changes. Newborn kittens purr while they feed. When they get older, some cats purr when they're happy. However, really scared cats purr, sick cats purr and female cats purr while giving birth. Some cats even purr when they are close to death. Scientists believe that stressed cats purr to reassure or comfort themselves - kinda like when we sing.

Most scientists think purring is a vibration of the muscles of the larynx and diaphragm. Others think blood flow to the soft palate at the back of the mouth causes the vibrating noise. Purring happen when nerves are activated within the voice box. Apparently, cats purr only when they want to.

Did you know that lions, leopards, tigers and jaguars can't purr but raccoons can?

Answer 4

There are two different meanings that are currently known.
1: Cats purr when they are happy. Could be when you're petting,
or anything else that gives them pleasure. Kittens will
sometimes purr while nursing.
2: Cats will sometimes purr when they are scared or in distress
(pain or discomfort). I believe they do this because it
comforts them.

Wow! Serena's answer is AWESOME!!! She deserves the 10 points just for doing all that typing!

Answer 5

Cats purr when they are happy and content and they also purr when in pain to sooth themselves. It turns out that cats have special wiring! The wiring travels from the brain to the muscles in the voice box, and this wiring is able to vibrate the muscles so that they act as a valve for air flowing past the voice box. The muscles work both during inhalation and exhalation, which creates the impression that cats can purr continuously. The air passes through the valve, which opens and closes rapidly to create the purring sound.

Answer 6

Nobody really knows. They purr when they're content, and they purr when they're in pain. We peepul don't even know HOW a cat makes the noise we call purring.

Answer 7

Purring means that they are happy. They have a special set of "vocal chords" just for that purpose. Big cats (tigers, lions, etc.) do not have this, and they do not purr.

Answer 8

Usually they purr because they are contented or happy. But sometimes they purr when they've been hurt too. It does seem to help them recover.

Answer 9

Cats purr involuntarily when they are pleased and content. If your cat purrs you are an exceptional cat owner

Answer 10

Cats purr for different reasons. They purr when they are comfortable in their surroundings and they can also purr when they are nervous.