I have a neighbor who seems pretty negligent with their cat, and it is always coming over to my place looking for attention. The cat is an outdoor cat, and I'm sure it is a scrapper, but it is also very friendly, so I am concerned over the amount of fur it is missing from its back, which seems to be getting worse. The cat doesn't look to be that old, maybe a few years, but it is now missing about a third of the hair on its back. It has no flea collar, so I'm wondering if it is some kind of parasite or something. There are some signs of lesions, but the cat doesn't stay still long enough for me to really examine it. This cat has also decided my house is his as well, darting inside any time I open the door. I don't really mind, but don't want to be tracking in feas or ticks if I can help it. Any ideas what could be causing the hair loss?