Jason Servis, the highest-profile defendant among more than two dozen people charged after a sprawling F.B.I. investigation, pleaded guilty to two counts related to the use of banned substances.
The excitement of thoroughbred horse racing — and many of the sport’s most vexing problems — are exemplified by the careers of the trainers Bob Baffert and Todd Pletcher.
The colt went on to become America’s 2-year-old champion and was favored to win the Kentucky Derby until he was scratched from the race with an injury. The doping case still hasn’t been adjudicated.