Abstract
<title>Abstract</title> <p>Background Cannabidiol (CBD) oil is used for pain management in dogs with osteoarthritis, but data on its effects using validated pain outcome measures are limited. This pilot study aimed to describe changes in validated pain-related outcomes following oral CBD administration in dogs with osteoarthritis and to generate preliminary data for designing future clinical trials. Results In this prospective, randomized, double-blinded, placebo-controlled crossover pilot study, ten client-owned dogs with radiographically confirmed osteoarthritis completed two 4-week treatment periods (CBD oil and placebo) separated by a 4-week washout, with pain assessed using the Helsinki Chronic Pain Index (HCPI), Liverpool Osteoarthritis in Dogs (LOAD) questionnaire, and the Canine Osteoarthritis Staging Tool (COAST/COASTeR). Changes in pain-related outcome scores were modest and variable, with greater within-dog variability for HCPI and LOAD than for COAST and COASTeR. Post hoc power analysis indicated that 24 to 132 dogs would be needed to detect CBD-related effects, depending on the outcome measure and effect size. One dog developed mild, self-limiting diarrhoea; no other clinically relevant adverse effects occurred. Conclusions Oral CBD oil was well tolerated in dogs with osteoarthritis. These pilot data provide effect size estimates to inform the design of adequately powered future studies.</p>