Last summer, the trainer Doug O’Neill was formally sanctioned after one of his racehorses at Hollywood Park in California tested positive for illegal drugs.
A year before, in 2010, O’Neill was punished for administering an illegal performance-enhancing concoction to a horse he ran in the prestigious Illinois Derby — the third time he had been accused of giving a horse what is known as a milkshake. Four months later, he was accused again of giving a milkshake to a horse in California.
Over 14 years and in four different states, O’Neill received more than a dozen violations for giving his horses improper drugs. O’Neill’s horses also have had a tendency to break down. According to an analysis by The New York Times, the horses he trains break down or show...