I don't think that Eight Belles could have overtaken Big Brown considering that Big Brown was the 2-1 favorite and undefeated going into the race. In addition, he had a comfortable lead at the time of the accident. As far as putting a horse to sleep on the track, I don't think it happens very often. I can only remember seeing it done one time before, but I don't remember the details. Terrible ending to such a beautiful animal.