Kentucky Derby-winning trainer Doug O'Neill said he will drop his appeal of a 45-day suspension in California stemming from a carbon dioxide overage in one of his horses in 2010 and will serve the suspension from Aug. 19 to Sept. 27.

During that time, when the boutique Del Mar Turf Club meet is being held, O'Neill's barn and horses will be under the supervision of his assistant, Leandro Mora.

"I think my time and money would be better invested by dropping the appeal," O'Neill said Wednesday. "Like everyone, as a trainer you are going 100 miles per hour six to seven days a week. It will give me a chance to slow down a little and help me try to be a better trainer when I come back. [During the suspension], Leandro will keep it as consistent and smooth sailing as possible."

O'Neill, who saddled Paul Reddam's I'll Have Another to win this year's Kentucky Derby and Preakness Stakes, was initially handed a 180-day suspension and fined $15,000 after a horse had a positive test for excessive carbon dioxide.

A hearing officer subsequently determined that the carbon dioxide level was not attributable to "milkshaking" -- a banned practice that involves treating a horse with a mixture of bicarbonate and/or other alkaline substances shortly before it competes -- but that O'Neill should be suspended under the trainer responsibility rule.

The revised 45-day suspension, which O'Neill initially said he would appeal because he questions the test findings, is contingent upon the trainer not having any Class 1, 2, or 3 drug violations within an 18-month period.

"I respect the racing board and I think we have a good racing board," O'Neill said, "but I don't agree with them. I am grateful they agreed there was no milkshaking, and now it is the trainer's responsibility rule that is in play."