Perhaps it is helpful to look at purring in the context of natural selection. Natural selection tells us that a particular behavior or trait will persist from generation to generation only if it is beneficial to an animal’s survival. For purring to exist in both domestic and wild cats, there must be something vital about the behavior. Purring is created by the vibration of the cat’s larynx and diaphragm, and therefore requires an expense of energy. If a kitty is sick, they would not use precious energy to purr unless there was a very good benefit.
I’m sure you have heard the expression that “cats have nine lives”. Similarly, veterinarians have an old saying that if you put a cat who has broken bones in a room with other cats, the breaks will heal. In fact, cats are amazing self-healers: they have fewer post-operative complications than dogs, have a lower incidence of bone and joint disease than dogs, and 90% of cats survive high-rise falls – I’m talking falls from 5 story buildings! (Robinson, et. al 1976) What could possibly account for these facts?
Maybe this has something to do with a cat’s uncanny ability to “heal by association”. Perhaps purring is part of the reason why, when we fall ill, having a cat sit on our laps can actually make us feel better. Whether it is simply the comfort of having a friend nearby, or whether it’s the vibrational frequencies of your kitty’s rumble, the joy of a cat purring on your lap is priceless.
Whatever the reason, I encourage you to take care of your cat. Keep him happy and purring and you’ll likely both lead healthier and happier lives.