I've heard of other animals (birds, cats) self-mutilating due to stress. (This happened to a cat of mine years ago--after I spent a week in hospital, he started attacking his own tail the night I came home. I tried to stop him took him in to the vet first thing in the morning, but he had already clawed/bitten to the bone--he had to have part of his tail amputated. He had to wear an E-collar for months, but eventually his tail healed and he learned to leave it alone.