Santa Barbara, who scored a pair of Grade 1 victories in the U.S. this summer, has died due to complications from a pelvic fracture. Santa Barbara, a 3-year-old daughter of Camelot, was trained by Aidan O'Brien, who bred her with his wife, Annemarie, in the name of their Whisperview Trading, for the Coolmore group and partners. She had been ruled out of the Breeders' Cup earlier this week due to a “setback.” O'Brien revealed to the Racing Post that the filly had been being treated for a fractured pelvis, the state of which worsened on Wednesday.   "Santa Barbara fractured her pelvis and unfortunately, the fracture displaced overnight,” O’Brien said. “It's obviously a real shame for everyone. She was a very talented filly." Pelvic fractures in horses are considered extremely difficult to treat; surgical repair is not a realistic option because of the location in the body and the heavy muscle mass and vasculature surrounding it. Internal hemorrhage is a feared complication, because bone can easily lacerate the important blood vessels, including the iliac artery, running near the bone structure. Even minor trauma – caused by a horse getting up or lying down in the stall, or bumping a gate or wall – can cause a minor, initially non-displaced fracture to displace or develop a lethal complication. Santa Barbara won her debut last year in Ireland in her only start as a juvenile. She made three Group 1 starts in Europe this spring, with her best finish coming when beaten a neck in the Group 1 Pretty Polly at the Curragh. She concluded her career with her two successful trips to the U.S. She first won the Grade 1 Belmont Oaks against her fellow 3-year-olds on July 10, defeating Con Lima by a half length. She then defeated older mares in the Grade 1 Beverly D. on Aug. 14 at Arlington, leading home Mean Mary by three lengths. Santa Barbara was a half-sister to last year's Breeders' Cup Mile winner Order of Australia, and to 2019 Breeders' Cup Filly and Mare Turf winner Iridessa. Her granddam was 2002 Filly and Mare Turf winner Starine.