I once had a cat that developed a nervous grooming habit after intestinal surgery. He would get a funny look in his eyes, then his hackles would go up, and then he would start frantically licking his shoulders. He created two bald spots that looked like someone had amputated his angel wings. I talked to the vet about getting him some kind of medication for OCD, but the vet didn't believe me. I ended up having to make the cat a nightgown to cover his wounds. After around 6 weeks or so the hair grew back, and I was able to let him run around in his birthday suit again.