Pharmacokinetics of a single feeding of pelleted cannabidiol in horses

Cannabidiol (CBD) has been marketed for animals, but there is little research to support lay claims of improved health and behavior. Studies have shown decreased anxiety behavior in rats, and increased activity in osteoarthritic dogs supplemented in CBD. Little research exists on horses. To better understand CBD supplementation in horses, this study monitored, pharmacokinetics and short-term safety for 3 CBD dosages. Eighteen Quarter Horse geldings were randomly assigned to 3 treatment groups based on CBD supplementation: 50 mg (TXT1), 100 mg (TXT2), and 250 mg (TXT3). Dosage was derived from manufacturer recommendations and existing literature on other species. Horses were fed a single dose of CBD pellets. Blood was collected at pre- and 0.5, 1, 2, 4 and 12 hr post treatment. Serum was extracted and stored for CBD and liver enzyme analysis. Plasma was collected for complete blood chemistry evaluation. Statistics were completed on liver enzyme concentrations using PROC MIXED procedure of SAS. Dependent variables included blood urea nitrogen (BUN), alkaline phosphatase (ALP), creatinine, and albumin. Experimental unit was a horse, with each serving as its own control. Fixed effects included time (pre and 4-hr) and treatment. Liver enzyme and CBC results were within normal parameters; however, treatment differences were observed for BUN (TXT1=15.33, TXT2=16.08, TXT3=18.33; P≤0.03) and creatinine (TXT1=1.42, TXT2=1.30, TXT3=1.50; P≤0.01). In other species, peak CBD concentrations occur approximately 2 hr post treatment. In this study, serum CBD concentrations were below the lower limit of detection in all TXT1 and 5 of 6 TXT2 horses. Peak serum concentrations were detected in 1 of 6 TXT2 horses and 5 of 6 TXT3 horses at 2 hr post treatment. This data can be used to support further research to determine correct and safe doses of CBD in horses