Opioids

Opioids are the prototypical analgesics, antitussives, and antidiarrheal drug class and are used extensively in veterinary medicine. This chapter provides an overview of the history of opioid use in veterinary practice and the current impact of the opioid crisis. Basic and clinical opioid pharmacology is presented including receptor classification, location, and regulation, pharmacokinetics, and pharmacodynamic effects. Considerations regarding route of administration as well as descriptions of selected full opioid agonists, partial opioid agonists, mixed opioid agonist–antagonists, and antagonists relevant to veterinary anesthesia and pain management are provided.