Abstract Background The safety of oral cannabidiol (CBD) and cannabidiolic acid (CBDA)-rich hemp oil supplementation in dogs with cancer receiving chemotherapy has not been investigated. Objectives To evaluate the safety, tolerability, and influence on doxorubicin exposure over time of oral CBD/CBDA-rich hemp oil supplementation in dogs diagnosed with high grade lymphoma undergoing CHOP chemotherapy. Animals Client-owned dogs diagnosed with lymphoma. Methods Dogs were enrolled in this prospective, double-blinded, randomized, placebo-controlled clinical trial to receive either CBD/CBDA-rich hemp oil capsules or placebo during one cycle of CHOP chemotherapy. Primary outcomes evaluated included adverse events during chemotherapy, quality of life scores and doxorubicin area under the...