This question is on behalf of a friend of mine who has a beautiful, medium-haired, male, mixed-breed. He has a habit of over-grooming. He rips out tufts of fur and sometimes cleans these areas until there is no fur left and there are weeping sores on the skin. The vet could not come up with a satisfactory reason/solution, so I thought maybe somebody here had an idea. He is flea-free (tried different products in case of allergy), an indoor/outdoor cat and is otherwise very active and healthy. We're a bit perplexed!!