Drug test warning: Research ongoing into effects of CBD on competition horses

The effects of non-psychoactive CBD products in horses remains the subject of ongoing research.
The effects of non-psychoactive CBD products in horses remains the subject of ongoing research. © Horsetalk.co.nz

Riders of competition horses across all spheres run the risk of a failed drug test if they give their animals non-psychoactive cannabidiol (CBD) products.

There is a growing worldwide market for cannabidiol products among people as authorities around the world ease restriction on its use as a supplement, or for medicinal use.

Cannabidiol is found in cannabis. It is derived from both marijuana and industrial hemp plants. Cannabidiol is not responsible for the psychoactive effects experienced in humans.

» Article: CBD Oil and Horses

However, it is believed to exert some anti-anxiety, anti-inflammatory, and analgesic effects in humans, and there is some evidence it can benefit those with epilepsy.

Increasingly, countries are easing restrictions, allowing its inclusion in over-the-counter supplements or by making it legally available by prescription.

However, the effects of non-psychoactive CBD products in horses remains the subject of ongoing research.

For now, it is likely to result in failed drug tests in both sport and racing horses.

The California Horse Racing Board recently issued a warning to this effect to trainers, warning that it can lead to a positive test for CBD and/or CBD metabolites in blood and urine.

For now, CBD is unclassified in California, which means a positive test result would amount to a class 1, category A drug violation, which can result in suspensions and substantial fines.

The board’s equine medical director, Rick Arthur, told the Thoroughbred Daily News: “The risk is so out of proportion to the reward that it would be foolish to use this product on a racehorse.”

A young cannabis plant in the vegetative stage
A young cannabis plant in the vegetative stage. Plantlady223 [CC BY-SA 4.0 ()], via Wikimedia Commons
The board’s position largely echoes that of the Racing Medication and Testing Consortium (RMTC), which issued a cannabidiol bulletin last year outlining the CBD situation.

CBD products must contain less than 0.3% of tetrahydrocannabinol, the principal psychoactive constituent of cannabis.

“As these over-the-counter products are produced without regulatory oversight, this requirement is largely unenforced,” the consortium noted.

“For the purposes of racing, the Association of Racing Commissioners International (ARCI) has designated CBD products as Class 3B substances. The ARCI designated products containing more than 0.3% THC as Penalty Class 1A substances.”

Turning to evidence on potential benefits in horses, the consortium noted that, at the time of the bulletin’s issue, it had found no peer-reviewed published research that evaluated the effects of CBD in horses.

“The purported effects – those that are used to market these products for horses – are based upon potential effects on the cannabinoid receptors and benefits of omega-3 fatty acids (of which CBD is not an optimal source).”

Horse sport’s lead body, the FEI, has declared all cannabinoids as banned substances on its Equine Prohibited Substances List (EPSL). Such products cannot be given to competition horses: “CBD (cannabidol), CBDA (Cannabidiolic acid) and THC (tetrahydrocannabinol) are cannabinoids, regardless of their source.”

Its drugs database lists “Cannabis – natural cannabinoids, synthetic cannabinoids and other cannabimimetcs” as prohibited substances. Like caffeine, it is defined in the FEI’s EPSL as a “specified substance”.

“Specified Substances should not in any way be considered less important or less dangerous than other Prohibited Substances. Rather, they are simply substances which are more likely to have been ingested by horses for a purpose other than the enhancement of sport performance, for example, through a contaminated food substance.”

Last year, the US Equestrian Federation issued a warning over the use of cannabinoids, noting that in the supplement market in recent years, cannabinoids have gained increased attention and “have become nearly mainstream”.

Cannabis Americana was offered as a cure for colic in horses.
In the early 1900s Cannabis Americana was offered as a cure for colic in horses. Before cannabis was outlawed in the United States in 1937, American veterinarians routinely prescribed equine colic medication which contained high doses of marijuana.
What does CBD do?

The effects of CBD claimed in the horse include treatment of inflammation, ulcers, laminitis, colic, and decreased anxiety.

It noted that researchers have published several articles regarding the effects of CBD oil including:

  • Pain reduction in dogs with osteoarthritis;
  • Decreased fertility in male mice; and
  • Decreased anxiety in humans.

“No research exists regarding similar effects in horses. These effects could occur because the horse does have cannabinoid receptors.”

The consortium notes that while US authorities maintain strict control over the prescription medication containing CBD to treat epilepsy, there is no similar control around over-the-counter products.

“Like other largely unregulated products, there are risks regarding purity, consistency, and safety.

“The lack of regulation poses a risk to the trainer of a positive finding and to horse health.”

It pointed to a published paper that reviewed the characteristics of 14 different CBD oil-based preparations available commercially in Europe.

Of the samples tested in that study, more than two-thirds of the products contained CBD concentrations that differed by more than 10% from the product’s label. One product contained a concentration of THC that would exclude it as a CBD product for the purposes of regulation by the Association of Racing Commissioners International, which would cause it to be regulated as THC with its corresponding Penalty Class of 1A.

The consortium also warned of the risk of dangerous contaminants in CBD products, noting a lack of regulatory oversight for the extraction of CBD from the cannabis plant.

It said it cannot make any recommendation regarding withdrawal guidance for CBD products.

“The variability among the many over-the-counter products makes performing research to provide reliable information impractical and costly.

“The concentration of CBD varies widely from label concentrations because, unlike prescription medications, there are no requirements for consistency with label concentration claims.

“Moreover, a trainer, veterinarian or regulatory authority testing these substances is futile because inconsistencies in concentration often occur between batches from the same manufacturer.

“The safest course of action for a trainer or owner is to consult a veterinarian regarding all horse health concerns, have a veterinarian diagnose any illness, and then prescribe FDA-approved products to treat the horse accordingly.”

The consortium’s executive director and chief operating officer, Mary Scollay, noted that many studies were currently exploring the effects of CBD products, including some involving horses.

“As it stands right now, there is no scientific basis for use in the horse,” she told the Thoroughbred Daily News.

Scientific findings may result in its reclassification, but she did not expect much of a change.


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