Thunderello, who was pulled up in the Frank J. De Francis Memorial Dash on Saturday at Laurel Park, broke the splint bone and chipped the sesamoid bone in his left foreleg, said his trainer, Scott Lake. Lake said X-rays taken the day after the race confirmed the injuries.The trainer said the breaks weren't related to the ligament tear in the same leg that had sidelined the promising 3-year-old for one year. Lake said Thunderello would probably remain in Maryland for about a month, while a decision was made on whether to retire him to stud or try to let him heal for a second racing comeback."I'm kicking myself for running him on a bad track," Lake said. "But at the same time it was just something that happened, It was just one of those freak things."Thunderello was the even-money favorite in the De Francis Dash after finishing second in the Breeders' Cup Sprint. He was running comfortably in second approaching the turn when he stepped awkwardly on the sloppy track. His jockey, Edgar Prado, immediately began pulling him up. Thunderello remained on his feet and left the track in the equine ambulance.