Only about 12% of horses tested for clenbuterol had measurable levels of the medication in 193 blood samples taken recently, according to a report made by Rick Arthur, DVM, Thursday to the California Horse Racing Board medication committee.

Arthur, equine medical director for the CHRB, had overseen the tests as part of additional information being provided as the agency mulls possible changes to California’s rule on allowable clenbuterol levels.

The CHRB at its January meeting had sent the clenbuterol issue back to the medication committee for further review. The blood tests were conducted not only to investigate the feasibility of using blood rather than urine tests, but to look into rumors that clenbuterol is administered to most horses racing in California.

“We found very little evidence that clenbuterol is being administered within 48 hours,” Arthur told the committee. “Several of the samples came close to 48 hours, but it doesn’t appear to be a problem. Certainly, we aren’t seeing 90% as has been rumored