I've heard that too... Sometimes the purr during surgury to calm themselves. Sorta like how they purr when they're relaxed, they purr when scared to try to put themselves in a more relaxed state of mind. Probably like how some people laugh in times of great stress.JungleKitty said:I agree...purring is said to have many meanings. I've read that cats purr if they are in pain to help sooth them.