FILE - In this May 4, 1996 file photo, jockey Mike Smith rides Unbridled's Song out of the gate at the start of the122nd running of the Kentucky Derby at Churchill Downs in Louisville,

 

              FILE - In this May 4, 1996 file photo, jockey Mike Smith rides Unbridled
FILE - In this May 4, 1996 file photo, jockey Mike Smith rides Unbridled's Song out of the gate at the start of the122nd running of the Kentucky Derby at Churchill Downs in Louisville, Ky. Prolific thoroughbred sire Unbridled's Song has died after a large mass was discovered in his sinus cavities and around the optic nerves. Taylor Made Stallions, where the horse stood his entire career, said the 20-year-old son of 1990 Kentucky Derby winner Unbridled suffered a rapid decline in health and was euthanized Friday, July 26, 2013. (AP Photo/Timothy D. Easley, File)