OHIO ANIMAL

Here's a creature from the past that has never been identified.  It was seen by G.G. Hibbard in Ohio in the 19th Century.  It was the size of a small hound.  It was white, with a black spot on its back.  Hibbard set his dogs on it, but it did them no harm except to knock them to one side with its head.  There seems to be no clue as to what this creature was.