Dog animagus. Might be too scared to go out as a stag if it were hunting season.
I gotta ask this though, would you resume your own form if you were killed in your animagus state? I'm really thinking about what might have happened if Crookshanks had actually caught Scabbers and tried to eat him or something.
Would you rather be a squib, unable to do magic, or a muggle, oblivious to the world of magic?