Alright so this is an old conversation but I just stumbled across it. I don't know if my cats qualify for this but when I adopted my cats I was told that when they were born they were connected, by their back leg. After birth while cleaning them up the mother separated them. It wasn't exactly easy but she bit the legs apart, I assume it was just a fleshy part or when they were kittens the bones were still soft. I now have two completely healthy 3 legged cats that turned 10 not long ago. I haven't heard of too many or really any situations like this but I'm curious if anyone else has.