Cricket has hyperesthesia, and she went after her tail--really bit into it. The vet tried medication (antidepressants), an e-collar, Bitter Apple . . . but nothing would keep her away from that tail.

Finally the vet amputated her tail. I was worried that she might zero in on another body part, but it's been about three years and she's been fine. She gets the skin twitches, but she doesn't chew on herself.