LOUISVILLE, Ky. – Shamrock Rose, last year’s champion female sprinter, exited an April 19 workout at Keeneland with an ankle injury that could lead to her retirement, trainer Mark Casse said Sunday at Churchill Downs. “I don’t know whether she is going to run anymore or not,” Casse said. “She’s done so much. She could come back, but by the time she comes back, we’re talking about fall and everything.” Shamrock Rose had been pointed toward Saturday’s Grade 1 Humana Distaff on Derby Day at Churchill Downs, a track over which she recorded a 25-1 upset in the Breeders’ Cup Filly and Mare Sprint last fall. The latter score was one of four consecutive stakes victories for her during the summer and fall of her 3-year-old year, with another highlight coming when she took the Grade 2 Raven Run at Keeneland in October. This winter and spring at age 4, she went winless in three starts, running fourth in the Grade 3 Hurricane Bertie at Gulfstream Park, third in the Grade 2 Azeri at Oaklawn, and fifth in the Grade 1 Madison at Keeneland. Casse said she underwent surgery after the ankle injury was discovered, and called her “healthy and happy.” There are no plans to breed her this spring, Casse said, noting that her owners, Manfred and Penny Conrad of Conrad Farms, are primarily racing focused. “More than likely she is going to be sold” this year, he said. A 4-year-old daughter of First Dude, she has won five of 13 starts and $968,962.