There's likely to never be another horse like Secretariat. His heart was literally three times the size of a average thoroughbred horse. Yes, THREE TIMES! It explains what happened fifty-years ago on June 9th, 1973. He destroyed the field in the final leg of the Triple Crown, the Belmont Stakes.
I thought you might enjoy seeing this short documentary from the movie "Secretariat," based on the chestnut colt who stole the headlines.