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

Abstract

Abstract Thirty stock type geldings (15 ± 3 y; 556 ± 63 kg BW) were used in a randomized complete design for a 28-d trial to evaluate the influence of cannabidiol (CBD) oil supplementation on health of mature horses by conducting a blood chemistry panel and evaluating the presence of banned substances. Horses were stratified by BW and age, and randomly assigned to 1 of 3 dietary treatments formulated with canola oil to provide.50 mg CBD/kg BW (TRT1; n = 10), 0.75 mg CBD/kg BW (TRT2; n = 10), or 0.00 mg CBD/kg BW (canola oil; CON; n = 10) only as determined by manufacturer (Arrowhead Labs). Treatments were individually fed and top-dressed onto a commercially available concentrate twice daily at 12 h intervals using attachable feed bags. Diets were formulated to meet or slightly exceed nutritional requirements for mature horses at maintenance. Between meals, horses were maintained in adjacent dry lots and received coastal bermudagrass hay ad libitum. Body weight was obtained, and body condition scores (BCS) were assigned every4 d. On d 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 (TVMDL; College Station, TX). Data were analyzed using PROC MIXED of SAS (v9.4), and the model included treatment, time, and the treatment × time interaction for BW and BCS. Blood chemistry variables on d 0 were used as a covariate and the main effect tested was treatment. Linear and quadratic orthogonal polynomial contrasts were used to partition sum of squares. Analysis of supplement samples revealed supplemented products contained lower CBD concentrations then indicated from initial testing. Therefore, horses in TRT1 and TRT2 received an average of 0.13 mg CBD/kg and 0.12 mg CBD/kg BW, respectively. Dietary treatments did not affect concentrate intake, BW, or BCS. Supplementation of CBD did not result in the presence of any banned substances in serum, including CBD, 7-carboxycannabidiol, 7-Nor-7-carboxycannabidiol, and tetrahydrocannabinol (THC). Following 28 d of supplementation, gamma-glutamyl transferase (GGT) responded quadratically (P = 0.06) to treatment, with a peak in GGT in horses receiving TRT2. Serum creatinine concentration tended (P = 0.06) to decrease with increasing inclusion of CBD in the diet. In contrast, the main effect of treatment on Ca concentrations was linear (P = 0.01) and characterized by decreased Ca values for TRT1 compared with TRT2 and CON. Canola based CBD oil was well-accepted by mature horses, banned substances were not detectible in blood, and blood chemistry parameters were not adversely affected as a result of supplementation; however, more information is needed to improve stability of CBD used in dietary products.