Oral cannabidiol increases thermal threshold in horses without physiologic adverse effects

Objective To investigate the effect of cannabidiol (CBD) on thermal and mechanical thresholds and physiologic variables in horses. Methods 6 horses (3 geldings and 3 mares) were enrolled in a prospective, randomized, masked crossover design from March 18 through May 3, 2025. Horses received 3.48 mg/kg CBD oil or placebo (sesame oil) orally every 24 hours for 3 days. Thermal and mechanical thresholds were determined at baseline and 4 and 12 hours after treatment administration on each day. Physiologic variables, including heart rate, respiratory rate, and rectal temperature, were recorded at the same time points. Data were analyzed using a generalized mixed model with significance set at P < .05. A Student t test was used to compare time points. Results Thermal threshold was elevated in the CBD group above baseline and placebo on day 2 at 12 hours and on day 3 at 4 hours. There was no effect of treatment on mechanical threshold. Overall least squares mean (95% CI) respiratory rate was 17 (15 to 20) and 18 (15 to 21) breaths/min in the CBD and placebo groups, respectively. There was no effect of treatment on heart rate or rectal temperature. Conclusions CBD provided intermittent antinociception as measured by thermal threshold. Clinical Relevance Oral administration of CBD appears safe and well tolerated at the dose studied.