2015 Kentucky Derby the lead in the homestretch. The race marked the fourth Kentucky Derby win for horse trainer Bob Baffert and the third win for Espinoza. The Kentucky Derby is a race for 3-year-old Thoroughbred horses. The 2015 field was determined by a points system that was introduced in 2013. The post position draw of the entries for the Kentucky Derby was held on Wednesday, April 29, 2015, at the Churchill Downs Racetrack clubhouse. American Pharoah was installed as the 5-2 morning line favorite. The day after the draw, Todd Pletcher scratched Stanford, stating that the horse was "fine" but they were
American Quarter Horse hence the nickname. Horses listed in the appendix may be entered in competition, but offspring are not initially eligible for full AQHA registration. If the Appendix horse meets certain conformational criteria and is shown or raced successfully in sanctioned AQHA events, the horse can earn its way from the appendix into the permanent studbook, making its offspring eligible for AQHA registration. Since Quarter Horse/Thoroughbred crosses continue to enter the official registry of the American Quarter Horse breed, this creates a continual gene flow from the Thoroughbred breed into the American Quarter Horse breed, which has altered many of the characteristics