Jockeys Calvin Borel and Emanuel Nieves avoided serious injuries in a two-horse spill Saturday at Louisiana Downs in Bossier City, La.   Nieves was transported to a local hospital and was diagnosed with a broken arm, according to an official with Louisiana Downs. Borel was examined by the track’s medical team and has been cleared to ride, the official said Saturday.   Nieves was thrown when his mount, Sneak Peek, stumbled in the stretch run of a $10,000 claiming race for fillies and mares at an “about” distance of 7 1/2 furlongs on turf. Borel’s mount, The Missing Piece, fell over Sneak Peek.   Sneak Peek was vanned off, according to the official chart of the race.  The Missing Piece was up immediately after the incident and galloped out with the field. Nieves is the third-leading rider at the meet and Borel, a Hall of Fame jockey, ranks 10th in the standings posted by Equibase.   :: DRF Bets members get FREE DRF Past Performances - Formulator or Classic. Join now!