Eclipse Award champion Improbable, whose first foals will race this year, was euthanized Saturday night after a loss of coordination led to a leg fracture. The son of City Zip was 8. A release from WinStar Farm, where Improbable was standing at stud, said the stallion began displaying ataxia, or a loss of coordination, “behind” on Saturday morning. He was shipped to Rood and Riddle Equine Hospital in Lexington, Ky., for treatment. “He was sent to Rood and Riddle [Saturday] morning to determine the exact cause of the ataxia,” WinStar president, CEO, and racing manager Elliott Walden said. “He was responding well to treatment, but went to lie down in his stall, and fell awkwardly. As a result, he broke his right tibia, which could not be repaired.” Improbable was trained by Bob Baffert for the partnership of WinStar, China Horse Club, and SF Racing. The blaze-faced chestnut won all three of his starts as a juvenile in 2018, including the Street Sense Stakes and the Grade 1 Los Alamitos Futurity. At 3 the following season, he won the Shared Belief Stakes and was second in both the Grade 1 Arkansas Derby and Grade 2 Rebel Stakes. Improbable put together his best season as a 4-year-old in 2020. After finishing second by less than a length to Grade 1 winner - and future WinStar stablemate - Tom's d'Etat in the Oaklawn Mile, he ripped off three consecutive Grade 1 triumphs, taking the Hollywood Gold Cup at Santa Anita by 3 1/4 lengths; the Whitney at Saratoga by two lengths; and the Awesome Again back at Santa Anita by 4 1/2 lengths, over champion Maximum Security. He was second by 2 1/4 lengths to that season's Horse of the Year Authentic in the Breeders' Cup Classic at Keeneland, finishing ahead of Grade 1 winners Global Campaign, Maximum Security, Tiz the Law, Tom's d'Etat, and Higher Power. Improbable retired after that effort with career earnings of $2,729,520, and was voted the 2020 Eclipse Award champion older dirt male. Improbable was about a month into his fourth breeding season at WinStar at the time of his death. He covered 177 mares in his first season at stud in 2021, according to The Jockey Club's Report of Mares Bred; 157 mares in 2022; and 94 mares in 2023, which proved his final full season. No figures are yet available for this year. Eleven 2-year-olds from Improbable’s first crop sold at last week’s breeze-up season opener, the Ocala Breeders’ Co.’s March sale, averaging $158,182. Juvenile racing in North America typically begins in April. “These horses are our life, and we work every day to take care of them the best way we know how,” Dr. Natanya Nieman, general manager and resident veterinarian at WinStar, said in the release. “The whole team is reeling. Improbable gave us many great moments to share with our partners, our team, and the whole racing community. It is tragic.”