Why do cat's purr?

Why do cats purr? The short answer is: we don’t know for sure.

What we do know about purring:
A feline purr is produced using the diaphragm and the laryngeal muscles (at the opening to the windpipe where the vocal cords live). The muscles twitch between 25 and 150 times per second, causing the vocal folds to separate. It continues during both inhaling and exhaling. It is theorized that this frequency improves bone density and promotes healing of bones and muscles. It can also have pain-relieving properties.  So purring may be a mechanism for self-healing, and might explain why we see fewer bone problems with cats than with dogs. Members of the felidae family (bobcat, cheetah, lynx, and puma) all purr, but the pantherinae family (lion, tiger, jaguar, leopards) have a different vocalization.

​When do cats purr?
Cats purr in a variety of situations and in response to different stimuli. Things that can stimulate feline purring include:

• Contentment: Sitting in a favorite human’s lap, lying in the sun, nuzzling up to a favored feline friend are all examples of situations that can induce purring. These are circumstances that seemingly represent true feline contentment.
• Wanting something: Purring can accompany feline requests for something they want, and might be heard at mealtime or when a kitty wants some lap time. This purring is often associated with some vocalization and animated behavior such as weaving in and out of their human’s legs.
• Fear or illness: Believe it or not, some cats purr when distressed or fearful. Such purring is commonly observed in a veterinary hospital setting, and can be quite audible. Some cats will purr when they're having difficulty breathing or are severely injured, possibly stimulating self-healing.
• Kitten-mother connection: Kittens begin purring when they are only a few days old. It is most noticeable when they are in close connection with their mama. In fact, kittens are capable of purring while nursing, and mama kitty typically purrs in response. Perhaps this purring behavior represents a means of bonding between a mother cat and her offspring.

Adapted from an article by Dr. Nancy Kay, DVM, DACVIM, http://www.pethealthnetwork.com/
Photo credit yellowcloud www.flickr.com