purring

Question
QUESTION: I have a 10 month old mixed breed kitten that has never purred and has a very soft meow.  he is up to date on his vaccines, and otherwise seems healthy and happy.  He was left at a local library in a carton and that's how I came to adopt him.

Do all cats purr?  What would cause a cat not to purr?

Any information you can give would be much appreciated.

Thanks so much,
Maureen

ANSWER: Some cats are loud purrers and some cats never purr. Some don't purr a lot until they are older. I had a cat like that. She never purred until she was 5 yrs old and I never could hear her purr until she was in her teens.

Some cats don't ever meow loudly either. My daughter's cat has a loud motorboat purr but barely makes sound when she meows.

Cats will purr when happy, in pain and dying.

---------- FOLLOW-UP ----------

QUESTION: Thanks so much for the info, but do you know what the mechanism is that causes purring?

Answer
I'm not sure anyone really knows but it involves the larynx and the cords near it, or the hyoid bone and/or blood vessels.  No one knows if the cat makes them vibrate or what they do to cause the purring.
Here is an interesting page on the subject:
http://cats.about.com/cs/catmanagement101/a/why_cats_purr.htm

Interesting factoid:
the only big cats that can purr are cougars, tigers and lions. Tigers and lions can only purr on an exhale in short bursts. House cats can purr for hours.