Why Do Cats Purr?
Everyone knows that cats purr, but how do they do it?
Purring seems to be caused by the cat's vocal chords being drawn together and apart so quickly that it creates a vibration in the larynx or voice box. This vibration is strong enough to be transferred throughout the cat's body. Other mammals, including humans, don't have the muscles to move the vocal chords that quickly.
Why do cats purr?
I suspect that purring is a form of communication. It is thought that the original function of purring was to enable a kitten to tell his mother that "all is well." This first occurs during nursing. A kitten can't meow and nurse at the same time, but it can purr and nurse without any problem. The mother often purrs back to reassure the kitten.
Older cats may purr when they play or approach other cats, signaling they are friendly and want to come closer. Cats also purr when they are contented, such as when they are petted, again giving the signal "all is well."
Are these the only times cats purr?
Strangely enough, cats can also purr when they are distressed. Sick and injured cats, and those in veterinary offices often purr. This is rarely because the cat is happy to see me! It is thought that this is the cat's way of reassuring and calming itself.
When a cat is purring, it's almost impossible to hear its heart or lungs very well. Many cats will stop purring if they see running water from a faucet. Do be confused if you see your veterinarian turn on the faucet in the exam room in an attempt to stop the purring so your cat can receive a more thorough exam.
Are cats the only animals that purr?
Cheetahs and ocelots are two other feline species that make a purr-like sound. But I have personally seen one other another animal attempt to purr. This was a small dog that, only while being petted, emitted a rhythmic low-pitched growl. As it turns out, this dog had been orphaned as a puppy but nursed from a cat that had recently had kittens. This dog was mimicking the purring sound as best it could and even used it at appropriate times.