Plasma and urinary exposure of cannabidiol and cannabidiolic acid in horses following consumption of contaminated feed.

Overview

• This study investigates how low-level contamination of horse feed with cannabinoids cannabidiol (CBD) and cannabidiolic acid (CBDA) affects their presence in horse plasma and urine.
• It reveals that even small, inadvertent intake of these compounds can lead to measurable levels in horses, which has implications for equine competition and drug testing.

Background and Rationale

• CBD and CBDA are natural, non-psychoactive cannabinoids found in hemp products.
• These substances are prohibited in competitive horses, but contamination of feed may expose horses unintentionally.
• There is limited data on how much these cannabinoids circulate and are excreted in horses following such low-dose, accidental consumption.
• The study aims to fill this knowledge gap by examining the concentration-time profiles of CBD and CBDA in plasma and urine after consumption of contaminated feed.

Study Design

• Subjects: Twelve Standardbred horses were selected for the study.
• Treatment: Each horse received feed intentionally contaminated with low doses (10-15 mg) of either CBD or CBDA.
• Administration: The contaminated feed was given twice daily for three days to mimic potential contamination exposure scenarios.
• Sampling: Plasma and urine samples were collected before exposure (to establish baseline) and during and after the treatment period to track cannabinoid levels over time.

Key Findings

• Before administration, no detectable CBD or CBDA was found in plasma or urine samples.
• After exposure:
  • CBD appeared sporadically in plasma, quantifiable in only some horses.
  • CBDA was consistently detected in plasma from most horses and remained detectable up to 48 hours post-exposure.
  • In urine, both cannabinoids were measurable in all horses.
  • CBDA concentrations in urine were higher and detectable for a longer duration compared to CBD.
  • The maximum urinary concentrations observed were significantly greater for CBDA than CBD.
• Considerable variability was observed between individual horses regarding the cannabinoid levels in plasma and urine.
• Neither cannabinoid was detectable in plasma or urine beyond four days after stopping exposure.

Interpretation of Results

• Systemic exposure to CBD and CBDA via low-level feed contamination is low compared to doses used therapeutically in horses or other species.
• Despite the low doses, both cannabinoids, especially CBDA, can be detected in biological samples, implying that even trace contamination can yield measurable results.
• CBDA appears as the dominant cannabinoid detected, likely due to its chemical properties or metabolism in horses.
• The data suggest that commonly used analytical tests might detect these cannabinoids following feed contamination, but the study did not aim to determine exact detection windows or match doping control sensitivities.

Implications for Equine Competition and Drug Testing

• Since CBD and CBDA are prohibited in competition, inadvertent contamination through feed could lead to positive tests despite no intentional administration.
• Drug testing laboratories and regulators should be aware that low-level cannabinoid detection may result from unintentional exposure.
• There is a need for cautious interpretation of low-level cannabinoid findings to avoid false assumptions about doping.
• This awareness could prompt the equine industry to monitor feed sources more closely and establish clearer guidelines regarding cannabinoid contamination.

Conclusions

• Low-dose oral intake of CBD and CBDA through contaminated feed results in measurable cannabinoids in horse plasma and urine.
• CBDA is predominantly detected, highlighting its significance in exposure assessments.
• The findings emphasize potential unintentional exposure risks and the importance of recognizing these when interpreting cannabinoid test results in horses.
• Future work may focus on refining detection thresholds and elucidating precise elimination times relevant for doping control purposes.