Your Questions About Split Sample Testing (And More), Answered

POSTED ON  |  10-06-2021

Over the past week we have received numerous emails asking questions about the split sample testing process, as the racing world waits for the next news in the Medina Spirit Kentucky Derby scandal. We got even more questions after Louisville Courier-Journal reporter Tim Sullivan revealed that the split sample taken after Medina Spirit's Kentucky Derby run hasn't yet been sent out for analysis.

We examined the process briefly last year when racing fans grew restless awaiting the split sample results from the 2020 Arkansas Derby card, but wanted to address a few of the questions that were specific to this case.

We spoke with Dr. Mary Scollay, executive director of the Racing Medication and Testing Consortium (RMTC) and former equine medical director for the Kentucky Horse Racing Commission, to learn more about how this regulatory process normally works. (Current staff at the commission are prohibited from discussing an ongoing case, particularly one like this where the split sample has not yet been tested.)

What's a split sample and how is it collected?

The split sample, or “B” sample, is collected at the same time as the primary sample, in the test barn after the race. Urine or blood is collected from the horse and subsequently divided into two containers. One of these is sent off for analysis by the laboratory contracted by the commission – in this case, Industrial Labs – for post-race testing. The other is stored under lock and key at the track at which it was collected.

If a lab finds and confirms a drug positive or overage in the primary sample, the trainer is notified and provided the opportunity to request to have the split tested. The trainer is allowed to select which lab will test the sample, and in many places is required to select a lab with a certain level of accreditation, like RMTC accreditation. All RMTC-accredited labs are capable of performing split sample testing.

How often are split samples negative, and what happens if they are?

If a split sample is negative, or if the split sample laboratory finds the substance in question at a level below the regulatory threshold, then there is no violation of the rules and therefore no ruling issued.

Scollay said that in her experience at the Kentucky commission, it was extremely rare for a split to come back negative.

“Maybe over 11 years, maybe there were four [cases where a split lab found a lower, legal level of a substance in question],” she said. “I can only think of one split in all those years where a laboratory reported a finding and the split laboratory did not detect it. And in that particular case it was a fairly obscure substance.”

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