Purrs Don't Always Signify a Happy Kitty
People will often say “oh, he’s purring,” and assume that it means that their kitty is happy. This may be true - especially if the cat is laying down, eyes half-closed and tail still or slightly wagging.
But purring can also be used to self-soothe. So a cat who is in pain or is nervous may also purr. Cats in veterinary clinics often purr, and we know these cats aren’t always happy! There is some thought that the low frequency emitted when purring helps to heal wounds, increase bone density and lessen pain and swelling.