No, I don't have XP, but I just read a post saying the dogs don't work then. So I took them out, but then I installed a clouded leopard. It appeared in the game, but the grey square still appears. So now it's just the clouded leopard (dowloaded from here, if you need the creator name, I can go find it, I think it was you but I'm not sure).
Oh, and if I have a quesiton about user-made varient skins, can I post that here? If not I'll take this down... but I installed a user-made varient and I placed 300 animals of that kind into an exhibit expecting to see at least 1 of the varient, but there wasn't one...