The use of cannabidiol (CBD)-rich hemp-based nutraceuticals is increasing in dogs and cats for disorders related to anxiety, seizures, cancer and pain. To date, there is little information related to appropriate dosing or long-term effects on serum chemistry or complete blood counts (CBC), and little data on the pharmacokinetics of single- or long-term dosing in dogs and cats. Single-dose pharmacokinetics and preliminary 12-week serum chemistry and complete blood counts are reported here showing short pharmacokinetic half-lives of cannabidiol in dogs and cats, with cats showing far lower oral absorption kinetics or rapid elimination suggesting dosing may differ between the two species. Fortunately, there were no changes in physical examination and few changes in the CBC and serum chemistry parameters suggesting the relative safety of oral supplementation over 12 weeks. One of the eight cats displayed a persistent rise in the serum alanine amino transferase (ALT) enzyme outside of the reference range and cats commonly displayed excessive licking and head shaking with administration of the oil. Based on these and other recent data, CBD-rich hemp nutraceuticals appear to be safe in healthy adult dogs, while more work in cats is needed to fully understand utility and absorption.