Why Cats Purr

To cat lovers, the sound of a cat's purr is like music to our ears. It signals to us that our cat is happy and content, which makes us happy, as well. There is nothing like having a relaxed, purring cat snoozing on your lap as you unwind in your favorite chair at the end of a hectic day. All the annoyances of the day fade into the background when confronted with the sound of perfect contentment.

We know that cats purr when they are happy, but the fact is that cats will also purr when they are frightened, or injured. On the face of it, this seems odd, but it really is not. Purring is not only a way for cats to express contentment; it is also a self-comforting mechanism. Sweet Pea used to purr like crazy whenever we took her to the veterinarian, and would crave comfort. It was as if she was trying to convince herself everything really was okay.

How do cats produce this sound that is specific to felines only? The exact mechanism of purring is still somewhat up for debate. According to Desmond Morris, author of Catlore, there are two competing theories. One is that the sound originates from the cat's circulatory system. Somehow, this theory goes, cats are able to speed up the flow of blood through the vena cava, the heart's largest vessel. The "turbulence" caused by this activity accounts for the sound we hear as purring. The other, more reasonable theory, places the origination of this sound around the vocal cords. Cats have the remnants of a second set of vocal cords, which vibrate to produce the "purr". I have heard of these two theories before, and I agree with Morris that the second seems much more believable. It certainly would account for the vibration we feel when we pet the throat of our purring cat!

Do big cats purr, as well? I know that cheetahs do, for instance. According to the Library of Congress, other big cats, including lynx and puma, also purr, while others such as the lion, tiger and jaguar, do not. I remember reading something once that stated that if an adult big cat roars, it does not purr, and vice versa. Interestingly, all young cats are capable of purring, and do so; behaviorists believe that it is how cubs communicate their status to their mother. For some, it is outgrown once the animal becomes an adult and is not needed anymore. For others, like our domestic companions, the capacity is retained for life.

I think that just as kittens purr to let their mother know all is well, our pets are giving us the same courtesy when we pet them and tell them how wonderful they are. They are honoring us with their contentment. Makes you feel rather important, doesn't it?
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