A complaint against Southern California trainer Doug O'Neill has been filed by the California Horse Racing Board alleging that a horse in O'Neill's care raced on an illegal non-steroidal anti-inflammatory drug last month at Santa Anita.

Stewards at Santa Anita set a hearing for the matter April 29.

O'Neill has had a running battle over total carbon dioxide testing with California authorities, who have cited him three times for exceeding the allowable level for TCO2. He served a 15-day suspension last year stemming from a separate TCO2 violation at Hawthorne Race Course in Illinois.

O'Neill filed a federal district lawsuit against the CHRB March 11 over the most recent TCO2 charge, which stems from an Aug. 25 race. The trainer alleges that the state's testing program is flawed and he is seeking an injunction against the regulatory agency prohibiting enforcement of its rules.

Also known as "milkshaking," the administration of alkalizing agents like bicarbonate of soda are designed to reduce fatigue levels in a horse or, some believe, to mask the presence of other drugs.

In its latest allegation against O'Neill, the CHRB announced March 18 that the Maddy Laboratory at University of California-Davis found that a urine sample taken from Separate Forest contained etodolac, a NSAID approved for use in humans and dogs. The positive was confirmed in a split sample tested at Iowa State University, according to the CHRB.

Separate Forest won the fifth race at Santa Anita Feb. 5. The use of etodolac is Class 3 violation, according to CHRB medication rules.