Evaluation of an Oral Supplemental Cannabidiol Product for Acceptability and Performance in Mature Horses

SIMPLE SUMMARY: Cannabidiol, better known as simply CBD, is one of the non-psychoactive compounds found in hemp. Its supplementation to horses is gaining in popularity as a potential alternative to conventional pharmaceutical treatments for a variety of conditions such as arthritis and anxiety. Despite potential advantages of CBD supplementation, it may have a negative impact on equine health and performance. More scientific research is needed to form recommendations for its use in horses; therefore, this study was designed to investigate supplementation of CBD oil over 28 days in 30 horses. Targeted levels of supplementation were to provide three levels for comparison (0.0 mg/kg, 0.75 mg/kg, or 1.50 mg/kg); however, the supplements collected during the study were analyzed to be substantially lower than targeted levels when tested at a verified testing facility (0.12 mg/kg and 0.13 mg/kg). At this level of supplementation, CBD oil was well-accepted, CBD was not detectible in blood samples, and blood chemistry parameters to assess liver and kidney function were not adversely affected as a result of supplementation. However, more research is needed to describe the discrepancy between formulated levels compared to tested levels of CBD supplements, in order to make recommendations for its application in the horse industry. ABSTRACT: Thirty stock type geldings (15 ± 3 years; 556 ± 63 kg BW) were used in a randomized complete design over 28 days to determine the influence of cannabidiol (CBD) oil supplementation levels on body weight, body condition, and blood chemistry. Horses were randomly assigned to one of three dietary treatments (n = 10 per treatment) formulated with canola oil to provide 1.50 mg CBD/kg BW (TRTA), 0.75 mg CBD/kg BW (TRTB), or 0.00 mg CBD/kg BW (canola oil; CTRL). Treatments were top-dressed onto concentrate and individually administered twice daily. Horses were maintained in adjacent dry lots and received coastal bermudagrass hay ad libitum. Body weight and body condition scores (BCS) were obtained every 14 days. On day 0 and 28, blood was collected via jugular venipuncture and serum was harvested to perform a blood chemistry panel and drugs of abuse screening at the Texas Veterinary Medical Diagnostic Laboratory. Data were analyzed using PROC MIXED of SAS (v9.4), and the model included treatment, time, and the treatment × time interaction, and linear and quadratic orthogonal polynomial contrasts to partition sum of squares. Analysis of composited treatment samples revealed lower CBD concentrations than indicated from initial testing by the manufacturer (0.13 mg CBD/kg in TRTA; 0.12 mg CBD/kg in TRTB). At this level of supplementation, canola-based CBD oil was well-accepted by mature horses, banned substances were not detectable in blood, and blood chemistry parameters were not adversely affected as a result of supplementation. More research is warranted to describe the discrepancy between formulated levels compared to tested levels of CBD in the canola-based supplement.