Effects of a Supplement Containing Cannabidiol (CBD) on Sedation and Ataxia Scores and Health

•The purpose of this study was to determine if a daily oral supplement containing CBD would cause sedation, ataxia or alterations in other health parameters during administration for 56 days.•Horses were randomly divided into two treatment groups, treated (supplement pellets containing CBD as Hemp Extract, 150 mg) or control (supplement pellets without CBD for 56 days.•Horses were monitored daily for clinical signs or adverse events and body weights were recorded weekly and blood work was performed on days 28 and 56.•Sedation and ataxia scores ranged from zero to two for all horses during the weekly examinations and there was no statistical difference between treatment groups and there was no treatment effects on blood parameters.•The CBD supplement (150 mg) was readily consumed and safe and did not result in changes in mentation, gait, or other health parameters, and no adverse clinical signs were observed during 56 days of oral administration. Supplements containing Cannabidiol (CBD) are available for horses, however, few studies have been published on their effects on behavior and health parameters. The purpose of this study was to determine if a daily oral supplement containing CBD would cause sedation, ataxia or alterations in other health parameters during administration for 56 days. Twenty clinically healthy adult Thoroughbred horses were housed in stalls. Before treatment was initiated, a complete physical examination, complete blood count (CBC) and biochemical panel were evaluated. In addition, horses were examined for sedation and ataxia using standard scoring systems. Horses were randomly divided into two treatment groups, treated (supplement pellets containing CBD as Hemp Extract, 150 mg) or control (supplement pellets without CBD). Horses were treated daily and sedation and ataxia scores were assigned by two masked observers once weekly for 56 days. Horses were monitored daily for clinical signs or adverse events and body weights were recorded weekly. A CBC and biochemical panel were repeated on days 28 and 56, two hours after administration of the supplement. The supplement was readily consumed by the horses and no adverse effects were seen over the treatment period. Sedation and ataxia scores ranged from zero to two for all horses during the weekly examinations and there was no statistical difference between treatment groups. There were no treatment effects on blood values, including indicators of anemia and blood proteins, liver enzymes, ki