This content is part of a free preview of DRF Plus. Click to learn more. Mentor Cane, a promising 3-year-old sprinter who finished second in the Grade 1 King’s Bishop Stakes on Aug. 24 at Saratoga, suffered a broken right hind leg during training Thursday morning at Belmont Park and had to be euthanized. Mentor Cane was one of two training fatalities Thursday as Skiddles n’ Bob, a 5-year-old mare trained by Chris Englehart, suffered fractured sesamoids in her left foreleg during a routine gallop over the training track and had to be euthanized. Mentor Cane, a son of Mizzen Mast trained by John Shirreffs for Ann and Jerry Moss, suffered his injury during a workout. Jockey Edgar Prado was aboard for the work, which Mentor Cane began about five lengths behind Mr Commons. About a quarter-mile into the move, Prado heard “a pop” and pulled the horse up immediately. However, Mentor Cane could not bear weight on his right hind leg and had to be euthanized on the track. “It’s heart-breaking,” said Shirreffs, who was working Mentor Cane toward a start in the Grade 1 Vosburgh here Sept. 28. Mentor Cane showed great promise when he won a maiden race by five lengths at Belmont on July 6 in his third career start. In the Grade 2 Amsterdam at Saratoga on July 28, he bore out while pressing the early pace and finished fourth, beaten 2 1/2 lengths. In the King’s Bishop, he was four lengths in front at the eighth pole before being run down by Capo Bastone. “It’s a shame because he could’ve had a great future,” Prado said. “He was learning to settle, learning to rate, seemed to be improving.” Skiddles n’ Bob, a daughter of Sharp Humor, was a 5-year-old mare who won 5 races from 29 starts, including her last start at Finger Lakes on July 22. She had been claimed several times throughout her career, most recently by Englehart on April 14 at Aqueduct. There was a third incident during training hours in which an unraced 2-year-old filly trained by Jason Servis dumped her exercise rider during a gallop. The rider, Cesar Garcia, was taken to a local hospital, but was reported to be okay by Servis.