An ingredient found in some calming supplements can put you on the wrong side of U.S. Equestrian Federation drug rules. Phenibut is a derivative of gamma aminobutyric acid (GABA), a central nervous-system depressant, and as such it’s considered a forbidden substance under those rules.

Although phenibut is sold as a nutritional supplement, it’s not approved as a pharmaceutical for horses or humans. The USEF sent out an alert about the substance in September after several positive findings in horses who had been given a supplement called Focus Calm from Uckele. 

In a statement, Uckele said that Focus Calm has been reformulated without phenibut and that none of its other products contains the substance. The company will exchange any non-expired, original Focus Calm for the new formula. If you have some, contact Uckele at customerservice@uckele.com or (800) 248-0330. 

This article originally appeared in the December 2015 issue of Practical Horseman.