Equestrian bodies issue warnings on CBD and citrus leaf derivative

Synephrine is found in the leaves of citrus trees, including lemon.
Synephrine is found in the leaves of citrus trees, including lemon.

A high number of positive tests for a banned stimulant that is found in the leaves of citrus trees and as an ingredient in herbal and nutritional supplements has prompted a warning from horse sport’s governing body.

And the US Equestrian Federation has also notified equestrians that positive tests for cannabinoids (CBD) from September 1 will be in violation of the organisation’s prohibited substances rules.

Synephrine found in common plants

Synephrine, a substance listed as a Banned Substance (Specified Substance*) on the FEI’s Equine Prohibited Substances List. It is a stimulant that can cause vasoconstriction, an increased heart rate and is used as a weight loss aid.

(*Specified Substances are those which are more likely to have been ingested by horses for a purpose other than the enhancement of performance, for example, through contaminated feed.)

Following several positive tests for the substance, the organisation has warned that synephrine may be found in the horse’s environment. Investigations into the sources of the positive cases are still ongoing, the FEI said.

In certain parts of the world, synephrine can be found in plants such as common rush (Juncus usitatus), Mullumbimby couch (Cyperus brevifolus) and the leaves of citrus trees (e.g. mandarin, orange, and lemon). Synephrine has also been detected in Teff grass hay in some countries.

Mandarin tree leaves contain synephrine, a stimulant that is used as a weight loss aid.
Mandarin tree leaves contain synephrine, a stimulant that is used as a weight loss aid.

It can also be found as an ingredient of herbal and nutritional supplements, and commonly found in the peel extract of bitter orange (also known as Seville orange) which is used as a flavouring agent.

Measures recommended to prevent positive findings include using reputable suppliers of hay, feed, and supplements, checking the horse’s environment for plants containing synephrine, and ensuring that any personnel taking supplements or other products containing synephrine wash their hands thoroughly after coming into contact with the substance. Additionally, it is recommended that samples are kept of batches of hay, feed and supplements given to competition horses to enable a thorough investigation to take place should the horse test positive for synephrine.

The FEI urges stakeholders to be vigilant of possible sources of synephrine in the horse’s environment and implement management practices to prevent contamination or inadvertent ingestion of the substance.

Cannabinoids “nearly mainstream” in equine supplements

The US Equestrian Federation (USEF) has noted that in the supplement market in recent years, cannabinoids have gained increased attention and “have become nearly mainstream”.

In 2018 Congress passed the Agriculture Improvement Act, also known as the “Farm Bill”, which defines “hemp” as both the plant Cannabis sativa L. and any derivatives of cannabis with less than 0.3% delta-9-tetrahydrocannabinol (THC). With the enactment of this bill, “hemp” is no longer considered a controlled substance under federal law, but THC remains a Schedule I drug with the Drug Enforcement Agency (DEA).

“The passage of the Farm Bill has created some potential confusion with respect to the use of these substances with competition horses.”

USEF Equine Drugs and Medications Rules prohibit cannabidiols (CBD) and their metabolites. While hemp does not contain more than 0.3% THC, it does contain CBD. CBD, both natural and synthetic forms, are likely to affect the performance of a horse due to its reported anxiolytic effects. This substance is no different than legitimate therapeutics that affect mentation and behavior in horses. It is for these reasons that USEF prohibits CBD and all related cannabinoids. Horses competing under USEF rules who test positive for natural cannabinoids, synthetic cannabinoids, and other cannabimimetics will be considered in violation of GR4 beginning September 1, 2019.

“It is important to note that analytical methods are being implemented to detect CBD and similar cannabinoids. Both USEF and FEI list natural cannabinoids, synthetic cannabinoids, and other cannabimimetics as prohibited substances.

“Caution is important when using these products as their composition widely varies and may not be representative of their label claims as there is no regulatory oversight from the FDA, nor guarantee of their safety in horses,” the USEF said.

“As published literature does not exist noting detection times of these substances in the horse, and because products can widely vary in their compositions and concentrations, detections prior to September 1 will receive warnings.” They will be considered to be in “Prior” violation if there are additional detections of cannabinoids following September 1.


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