HIWU ruling raises questions over supplement warnings and banned substances

Gary Greiner’s case put a familiar backstretch problem under a harsh spotlight: a supplement that looked ordinary on the shelf, a banned substance buried in the fine print, and a regulator whose warning system the arbitrator found too confusing for the people expected to follow it.

The Horseracing Integrity and Welfare Unit charged Greiner with possession of Piper Methysticum, also identified as Kava or Kava Kava, a Category S0 banned substance, tied to a June 20, 2025 event date at Emerald Downs in Auburn, Washington. Greiner’s hearing was held remotely on April 16, 2026. In the decision, he was described as a high-level trainer licensed for about 40 years, with 20 years of experience operating his own stable in Santa Rosa, California.

What made the ruling resonate beyond one barn was not simply the possession charge. The decision noted that HIWU investigators had searched Greiner’s barn in July 2023, when EasyWillow was already on the premises, and searched again on June 10, 2025. Eight days before that later search, HIWU had alerted investigators to look for EasyWillow after learning the supplement contained Kava Kava. That sequence left horsemen with a hard question: if the product was already in circulation and the substance was already known, why did the warning system not reach trainers and owners sooner?

That is where the arbitrator’s criticism landed hardest. HIWU’s substances lookup says it includes HISA’s controlled and banned substances database, but it also warns that no representation or guarantee is made as to its accuracy, reliability or completeness. HIWU’s educational material on S0 substances adds that a substance can still be prohibited even if it is not specifically named on the Prohibited List. The ruling said the naming issue was confusing to the average reasonable horse trainer, because the connection between Kava Kava and Piper Methysticum was not obvious in the database results.

Finish Line Horse Products’ EasyWillow page adds another layer to the problem. The product is marketed as a daily supplement for temporary relief of minor stiffness and soreness due to overexertion, and it lists herbal ingredients such as white willow, devil’s claw, yucca schidigera, feverfew, turmeric and boswellia serrata. The page does not plainly flag Kava Kava, which is exactly the kind of gap that can turn a feed-room decision into a regulatory case.

The broader lesson for horsemen is blunt. HISA’s ADMC rules were approved by the FTC on March 27, 2023 and implemented on May 22, 2023, and the national integrity system now depends on trainers reading supplements as carefully as they read condition books. Greiner’s case showed that even a veteran horseman can be exposed when product marketing, ingredient terminology and the banned-substances database do not line up cleanly.