I would "yank" my cat right out of that vet's office. If she truly did yank the hair out and not shave it, what the hell??? Find another vet, report this one and keep asking questions until you get answers. That's what you're paying them for. They're there to serve you, not the other way around. When my cats are stressed at the vet's, which is every time, their hair will come out in clumps. And my Creamsicle has a hair follicle infection right now and it comes out as though it was a paintbrush. Do you feel any little bumps or scabs on your cat? If so, this might be the problem. At any rate, just keep searching for the right vet and demand answers, in a polite way, of course.