Cats also purr when they are in pain to comfort themselves, but
mostly it is because they are happy and they love you. Basically,
to express their emotions.
View page
Cats purr when they are happy. The more they purr they happier
they are.
View page
There is no illness that causes a cat to purr. Cats purr when
they are happy, content, and socialized. This includes non
domesticated cats.