One of mine has a strange patter of hair loss. I'm not sure how long it's been like this but now I've noticed it it's been troubling me. It's in a kind of U shape behind he front legs running from halfway up her body, under her belly and halfway up the other side. The belly is quite sparse with hair too. I see no behavioral changes. She's around me a lot and I see a lot of her grooming, but I've never seen her groom these ares - I'm not even sure she could reach them. I've checked for fleas and she has no problem with me handling these areas and there's no sign of a skin problem. My cat flap is quite high off the ground and she does have to pull herself through it to get in, though it doesn't stop her using it. There should be a picture there - not sure how this works - I attached one too. Does it seem likely that the act of pulling herself through that might cause that sort of hair loss? I put the brick there to see if that will help.