To show contentedness
We are familiar that cats like to purr during their meals. A cat curled up on a lap, enjoying themselves alone. Contentedness can be the best reason why by your cat purr.
Cats often are heard making a loud purr, so there must be other reasons besides contentedness. But many cat owners would ask why a contented cat has any reason to show their contentedness?
To show affection
Cats like to approach their favorite people by purring loudly in order to show their affection. Of course this kind of purring belongs to affectionate behavior.
Even though there is not enough proof to prove this theory, it sounds logical that this kind of purring is to express affection.
To show passiveness
Cats often purr after a serious incident, such as trauma, accident or injury. Actually they seem to purr louder before a severe incident occurs. This demonstrates neither contentedness nor affection, while demonstrating passiveness would be much more reasonable explanation.
The healing properties
Purring has healing qualities, cats are ready to take every chance to get a bit of healing.
Different from other theories, this one also doesn’t belong to any certain situation in which you might hear a loud purr.
Cats purr are evaluated to be at a frequency of between 25Hz and 150Hz. The frequencies have been proven to affect the physiology of most animals.
In addition, cats are proved to be tenacious and tough little critters, which can survive illnesses and injuries that would kill a human many times. They can fall from a tall building, or consume fatal poisons, but finally recover without any lasting effect.
My cat even seems to appreciate the odd meal of toxic substances, so we now have locked everything we think it is toxic.