Medina Spirit and two other Bob Baffert-trained horses – Concert Tour and Beautiful Gift – completed the first round of testing ahead of the Preakness Stakes, the Maryland Jockey Club and 1/ST Racing said in a statement Thursday.

The organizations said in a joint release three tests have been conducted on Baffert’s horses. The Maryland Racing Commission took two — on May 6 and May 10. The Maryland Jockey Club and 1/ST Racing took the third on May 11.

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The May 6 samples were screened for prohibited and therapeutic substances and were reported to be all clear, the news release said. The results of the May 10 and May 11 samples are set to be revealed Friday.

"1/ST RACING is committed to achieving the highest level of horse care and safety standards in Thoroughbred racing. We have been an industry leader in instituting processes and protocols that have led to nationwide medication reform and increased accountability and transparency," 1/ST Racing CEO Craig Fravel said in a statement. "While we acknowledge the challenging circumstances that prompted this further need for transparency, it reflects, above all else, that the principles of integrity, accountability, and safety in our sport are non-negotiable."

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Medina Spirit will be able to ride in the Preakness under "rigorous conditions to entry along with a binding commitment from Bob Baffert to full transparency of medical and testing results that will allow for all results to be released to the public," the Maryland Jockey Club and 1/ST Racing announced earlier this week.

Tuesday’s decision came just hours after Baffert revealed that a "possible source" of positive drug test following the Kentucky Derby may have been from a fungal ointment that contained betamethasone.

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Baffert had previously defended his horse.

Fox News’ Paulina Dedaj contributed to this report.