DEL MAR, Calif. – The workout on Thursday by Imperative here at Del Mar is being investigated by the state racing board, as it appears it came prior to when it should have been allowed owing to Imperative being placed on the veterinarian’s list for shock-wave therapy. Imperative, who has not raced since April and is pre-entered in the $1 million Breeders’ Cup Dirt Mile on Nov. 3, is listed on the California Horse Racing Board’s website as having been placed on the vet’s list on Oct. 23 for shock-wave therapy. His trainer, Bob Hess Jr., confirmed on Friday that he was treated that day. According to CHRB rules pertaining to the veterinarian’s list, a horse placed on the list for shock-wave therapy “may not workout (sic) for 72 hours after being placed on the list without the permission of the official veterinarian.” Imperative worked shortly after 7 a.m. on Oct. 26. Horses treated with shock-wave therapy – the medical term is extracorporeal shockwave therapy (ESWT) – cannot race for 10 days after treatment. “The day after treatment is the first day on the Veterinarian’s list,” according to a memorandum on the topic from May of 2012. “The horse will be automatically removed from the Veterinarian’s list for ESWT on the 11th day,” the memorandum reads. The “day after treatment” is also apparently when the clock starts to run regarding being able to work out. Based on that timeline, Imperative went a day sooner than he should have, though it’s certainly understandable how one could treat a horse on Oct. 23 and think 72 hours later, Oct. 26, they’d be good to go. “Ignorance is not an excuse,” Hess said. “I did not understand the rule correctly.” Dr. Rick Arthur, a veterinarian who is the equine medical director for the California Horse Racing Board, said the situation “will be assigned to an investigator to confirm the facts.” “If warranted, a complaint could be filed,” he said. If a violation is found, cases like this typically result in a fine. Regardless, by being treated on Oct. 23 Imperative will come off the vet’s list the day of the Dirt Mile. Hess said he timed the treatment so that Imperative would be fine to run in the Dirt Mile. Hess volunteered that he used the treatment for Imperative’s glutes and his left front hoof. He also said American Pastime, who is heading to the Breeders’ Cup Sprint and worked on Friday, had shock-wave therapy as well on Oct. 23, “for his feet and ankles,” Hess said. “It’s therapeutic,” Hess said. In other Dirt Mile developments Friday, Giant Expectations worked five furlongs in 1:00.80 at Santa Anita for trainer Pete Eurton, and Awesome Slew went a half-mile at Churchill Downs in 47.60 seconds for trainer Mark Casse. – additional reporting by Steve Andersen