How Do Cats Purr, and Why Do They Do It?
A cat’s purr starts as vibrations in the blood vessels of the chest, around the heart. The vibrations travel up the air passage to the neck area, where we hear them as a low rattling hum. It has nothing to do with the true voice of the animal. No one is sure why cats purr. Cats usually purr when they’re content, but they sometimes purr when sick or injured.
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. Purring may also be a cat’s way of accepting another cat or a person. Kittens begin purring about a week after birth. But a mother cat purrs to her kittens soon after they are born.
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. 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.
As the kitten grows into adulthood, purring continues. Purring is a unique vocal feature in the domestic cat. 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.