Robertino Diodoro, who finished third in the trainers’ standing at the recently concluded Oaklawn Park meet, has been suspended 30 days by Arkansas stewards after a horse he trained tested for an excessive level of total carbon dioxide in the blood, according to a ruling. Diodoro will serve 15 days of the suspension during the beginning of the Oaklawn 2023-24 meet in December later this year after declining to appeal the finding, according to the ruling. The other 15 days of the penalty will be stayed, provided that he does not have any Class A or Class B medication violations over the next year, the ruling said. Aristocracy, trained by Diodoro, tested at 42.3 millimoles per liter of blood of total carbon dioxide, according to the ruling, after finishing sixth in the $200,000 Bath House Row Stakes at Oaklawn on April 22. Total carbon dioxide levels of 37.0 millimoles per liter of blood are considered a violation in Arkansas. Diodoro said on Monday that he did not administer any substances to Aristocracy that would boost his total carbon dioxide and that he accepted the penalty to “move on.” “We’ve had the same program for a long time, haven’t changed anything in 10 years,” Diodoro said. “I could drag my feet and try to figure out the 10 ways this could happen, all the possibilities, but I’m not one to do that. I decided to take it like a big boy. It’s an unfortunate thing and it ticks me off, but I’m not one to drag these things out.” Though total carbon dioxide levels in horses can vary across a relatively wide range, regulators set the 37.0 limit after testing revealed that a level above the limit would be indicative of unnaturally boosting a horse’s ability to process lactic acid in the blood, usually by administering a solution containing bicarbonates and vitamins, a practice known as “milkshaking.” Regulators began cracking down on the practice in the late 1990s after it was revealed that some trainers were routinely milkshaking their horses. Violations are now extremely rare in racing. Diodoro had 61 winners from 266 starts at the recent Oaklawn meet, a strike rate of 23 percent, with purse earnings of $2.9 million. In 2022, he had 191 winners from 894 starters, for a rate of 21 percent, with purse earnings of $6.8 million.