It starts out feeling like little pimples. If your feral allows you to pet him, when you remove your hand, chances are good that it'll be covered w/cat hair. And the pimples have heads on them and you can pick one off like you would pull sections out of a paint brush. They're very itchy and the cat is just miserable w/it. Dr. Lee said that it occurs mainly in horses from standing in dirty stalls. Cgirl probably gets it from the litterbox even though I clean them several times a day. But, as I mentioned, her immune system is compromised so she can get things that my other cats wouldn't. Left untreated they can lose all their fur and it's so itchy, it's like having poison ivy. As it is, Cgirl lost hair on the top of her head and her chest. I went on a cleaning binge but Dr. Lee assured me that it's nothing that I was or was not doing. Hope this helps.