Looks like the Breeder's Cup horse are running clean according the The Horse. Here is a good report on the methods, and the consequences of doping in the Breeders Cup series.
None of the horses that participated in this year's Breeders' Cup World Championships Oct. 24-25 at Santa Anita tested positive for steroids, blood-doping agents or TCO2 (bicarbonate), according to Pam Blatz-Murff, senior vice president of operations for the Breeders' Cup.
However, as of Nov. 8 test results for any other prohibited substances were not available because of the testing process used by the California Horse Racing Board (CHRB).
Under Breeders' Cup and CHRB rules banning anabolic steroids, tests were conducted on the first four finishers and one additional horse selected at random in each race. The steroid rules, in place for the first time at the Breeders' Cup, called for disqualification and purse distribution, and a possible one-year suspension for the trainer of any horse testing positive.
The blood-doping tests were conducted under "out of competition" rules 10 days before the races. Any horse testing positive would have been ineligible for competition, with the trainer facing suspension. The TCO2 tests were conducted in the detention barn prior to each race, with a purse forfeiture and trainer sanctions for any positive tests.
Rick Arthur, DVM, equine medical director for the CHRB, said any positives for other prohibited substances would not be reported until the split-sample process is completed. Under CHRB rules, a test is not considered positive until a suspect sample has been confirmed by another testing lab.
Under CHRB rules, the primary testing lab has 21 days to report any positives. The trainer of the horse in question then has 72 working hours to request that a split sample be sent to a confirmation lab and then has five additional working days to make arrangements with one of the six labs available for split-sample testing. Once the lab receives the split sample, it has 28 days to report the results to the CHRB. At that time if the split sample confirms the positive, a complaint is filed against the trainer.