Jockey Eddie Castro will be out of action a minimum of three months after sustaining a hairline fracture of his back in a spill Saturday at Belmont Park. Castro, 26, will not require surgery, but he will have to wear a back brace for period of time. Castro was expected to be released from North Shore University Hospital in Manhasset, N.Y., on Tuesday. Doctors at North Shore told Mike Gonzalez, Castro's agent, that Castro could be out three to six months. Gonzalez said he hoped to learn more when he and Castro talk to doctors on Tuesday before Castro is discharged. "He's an athlete, he's a quick healer," Gonzalez said of Castro, who he has represented for a decade. On Saturday, Castro was aboard Royal Brush when that horse broke the cannon bone in his left foreleg at the sixteenth pole in the fourth race at Belmont Park. Royal Brush was euthanized. Castro was enjoying a solid year with 119 wins from 876 mounts. Through Saturday, Castro's purse earnings were $6,766,461, placing him 15th in the nation, according to Equibase statistics. This year, Castro won four Grade 1 races, including the Wood Memorial on Toby's Corner, the Acorn and Coaching Club American Oaks on It's Tricky, and the United Nations at Monmouth on Teaks North. At the current Belmont meet, Castro was 9 for 95, tying him for 11 th in the standings. At Saratoga, Castro finished as the seventh-leading rider with 19 wins from 153 mounts.