INGLEWOOD, Calif. - Hall of Fame trainer Bob Baffert did not violate any California Horse Racing Board rules when seven of his horses based at Betfair Hollywood Park died suddenly during a 16-month period ending in March, the racing board was told on Thursday. Equine medical director Dr. Rick Arthur told the racing board that necropsy reports conducted on the horses revealed no presence of illegal medications, but said that the high incidents of such deaths in one stable was exceptional. “Statistically it is extremely abnormal,” Arthur said toward the end of a nearly hour-long presentation to the board. “We couldn’t find anything. It doesn’t change the fact we don’t have an answer. It does say there is something wrong here.” Baffert, who has one of the biggest and most successful stables in California, declined to speak about the board’s findings via telephone. In a text message sent Thursday afternoon, Baffert wrote, “I am gratified that CHRB and staff completed its investigation and found there was no wrongdoing. My focus will continue to be on providing the best care for my horses.” The deaths of the seven Baffert-trained horses occurred from early November 2011 to March of this year. The most prominent runner to die was Irrefutable, who collapsed after finishing second in the Vernon Underwood Stakes at Hollywood Park in November 2011. The racing board’s investigation was completed last month. Arthur said the investigation found that five of the seven horses died of cardiopulmonary failure, one of equine protozoal myeloncephalitis, and one from rat poison which is believed to have led to abdominal hemorrhage. Five horses were stricken during workouts or while galloping, one died during a race, and Irrefutable died immediately after the race. “Most of these have fairly reasonable clinical explanations,” Arthur said. Arthur said the racing board’s investigation involved searching for blood doping agents at Baffert’s barn following the third incident, which occurred in January 2012. The tests included screening for medications such as clenbuterol, ractopamine, zilpaterol and anabolic steroids. The bronchial dilator clenbuterol was found in 25 percent of the tested runners, according to Arthur’s report. Clenbuterol can be used therapeutically but is not allowed to be present in a horse’s bloodstream on raceday. More recently, environmental tests were conducted on Baffert’s stable at Hollywood Park and of that racetrack’s synthetic racing surface. The testing was conducted in August and September of this year, but did “not indicate an environmental toxicant of concern,” according to the report. By the time of the seventh death, in March, the racing board had launched an official investigation. The urine in all seven horses was tested at a necropsy lab in San Bernardino, Calif., according to Arthur’s testimony. Arthur said that all seven of Baffert’s runners had been treated with thyroxine, a thyroid hormone used to treat hypothyroid conditions. The medication must be prescribed by a veterinarian, Arthur said. Baffert told Arthur during the investigation that he used thyroxine on all his horses, but quit last March after the seventh died. Arthur said it was rare for the medication to be used that extensively. “I haven’t found a barn that uses it on all their horses,” he said. “It was legally dispensed and reported as labeled. It was within their right to do so. There is no violation of any rules. You want to have an ‘Aha!’ moment, but this was used in his stable all the time.” Arthur said that sudden deaths typically occur at a rate of 1 in 8,000 Thoroughbred starts, and 1 in 158,000 horse training days. From a period of July 1, 2007 to June 30, 2013, which covers six fiscal years, there were 78 cases of sudden deaths in California Thoroughbreds – 23 in racing and 55 in training. The training category included horses going through workouts, or galloping, jogging or ponying. During that period, three trainers had two horses die while racing – Baffert, Keith Craigmyle, and Doug O’Neill. Of the 55 training cases, Baffert had six, including an incident in July 2010. Steve Sherman had three sudden deaths in his barn, while Jeff Bonde, Jorge Gutierrez and John Sadler had two each. The highest number of racing fatalities in the state during that span was seven during the 2010-11 fiscal year. Beginning that year, there was a spike in training sudden-death fatalities, which rose from 5 in 2009-10, to 12 in 2010-11, 15 in 2011-12, and 11 in 2012-13. Arthur told the racing board that in the first four months of the current fiscal year, from July through October, there have been three sudden deaths – two in racing and one in training. In summarizing his report, Arthur said the rash of sudden deaths in the Baffert stable “at one track in a relatively short period of time is unexplained.” “All of these horses have pathological changes that you couldn’t do intentionally if you wanted,” he said.