(WHAS11) -- Doug O'Neill, the trainer of Derby winner "I'll Have Another" could face a suspension in California after one of his horses was found to have an elevated level of total carbon dioxide.
The process is called "milk-shaking" and it's designed to reduce fatigue and enhance the horses' performance.
It wouldn't be the first time O'Neill has been punished for the infraction.
This is his third charge in California and his fourth in his career.
O'Neill who's at Pimlico preparing "I'll Have Another" for the Preakness, denies the charge.