I have an apbt. I got a dog door for her about a year ago. Several months ago she started developing a shiny bald spot on her head. I took her to the vet and they said it looks like she rubbed it on something. I think she was using the door a little less, and the hair started growing back. Shes using it alot now, and there is a shiny bald spot again. It doesnt seem to be bothering her, but I dont want it to eventually rub to far and get infected, but I have to keep the dog door open while I'm at work so she can go in and out. Anyone else have this problem?