In the spring of 2007, one of our cats started licking her belly to the point of removing all of her fur. She also removed much of it from her upper hind legs. I took her to the vet a couple of times. First we tried antihistamine, in case it was a seasonal allergy. When that didn’t work, he suggested Prozac, since it sometimes helps pets with weird compulsions. We tried Prozac for a couple of months, but it only seemed to make her dopey and wobbly on her feet without stopping the over-grooming behavior. Ultimately, we gave up the Prozac and just accepted that we have a silly-looking cat with a bald belly and thighs. It’s otherwise harmless, and fortunately it doesn’t cause her to upchuck hairballs all over the house.
“What is over-grooming in cats?”
http://www.cat-world.com.au/OvergroomingInCats.htm