US Equestrian Federation Issues Warnings On Two Prohibited Substances by Paulick Report Staff|05.28.2019|8:38am A plethora of competition horses have tested positive for synephrine, a banned substance found in the leaves of citrus trees. Used in herbal and nutritional supplements, the US Equestrian Federation has issued a warning regarding the use of the stimulant, which can cause vasoconstriction, increasing heart rate and aiding in weight loss. Synephrine is listed as a “specified substance,” meaning that it is more likely that the horse ingests it accidentally, as in through contaminated feed, rather than intentionally as a performance-enhancement aid. Synephrine can be found in some plants around the world, including mandarin tree leaves; it has also been detected in Teff grass hay. It has also been used as a flavoring additive. To combat positive drug tests for synephrine, it's recommended horse owners and riders buy only from reputable hay, feed and supplement companies; they should also check the horse's environment for possible plants that may contain the substance. Anyone who handles the horse should wash their hands well after coming into contact with synephrine. It's also recommended that samples be kept of all feed, hay and supplements fed to competition horses in case an investigation for the substance should arise. Additionally, the US Equestrian Federation has put riders and owners on notice that positive tests for cannabinoids (CBD) after September 1 will be in violation of the prohibited substances rule. Though cannabinoids have become “nearly mainstream” in equine supplements, USEF Equine Drugs and Medications Rules prohibit cannabidiols (CBD) and their metabolites. USEF notes that both natural and synthetic forms of CBD can calm sport horses both mentally and behaviorally, and are therefore illegal to be used in competition. Testing methods are being determined as there are no published findings of detection times of CBD in horses; positive test results prior to September 1 will receive warnings. Read more at HorseTalk.