A review of analgesic compounds used in food animals in the United States.
Extralabel drug use for pain relief in the United States is regulated under the Animal Medicinal Drug Use Clarification Act. Agents that may provide analgesia in livestock include local anesthetics, nonsteroidal antiinflammatory drugs, opioids, α2-agonists, and N-methyl-d-aspartate receptor antagonists. The challenges associated with providing pain relief in food animals and the salient pharmacokinetic and pharmacodynamic features of the analgesic compounds that could potentially be used in livestock are reviewed. The potential use of novel agents such as bicarbonate, magnesium, ethanol, and gabapentin to augment analgesia is also discussed.