Natural Food Phytochemicals as Anesthetic, Analgesic, and Euthanasia Agents in Food-Producing Animals

• Grant number: 25/21104-6
• Support Opportunities: Scholarships abroad - Research
• Start date: October 01, 2025
• End date: September 30, 2026
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Clinics and Surgery
• Principal Investigator: Antonio José de Araujo Aguiar
• Grantee: Antonio José de Araujo Aguiar
• Host Investigator: Robert Joseph Brosnan
• Host Institution: Faculdade de Medicina Veterinária e Zootecnia (FMVZ). Universidade Estadual Paulista (UNESP). Campus de Botucatu. Botucatu , SP, Brazil
• Institution abroad: University of California, Davis (UC Davis), United States

Abstract

Conventional drugs used for pain relief, sedation, anesthesia, or euthanasia in food animals can cause the accumulation of harmful residues in foods derived from these species (e.g., meat and meat products, milk, and others) as well as in the environment (e.g., groundwater contamination, consumption of remains by wildlife). Methyl salicylate and L-carvone are hydrocarbon compounds extracted from aromatic plants, Gaultheria and Mentha, respectively. They are considered safe for addition to foods and classified by the Flavor and Extract Manufacturers Association of the United States (FEMA) as "Generally Recognized As Safe" (GRAS). These phytochemical extracts can act on cellular target receptors recognized as essential for the expression of anesthetic and analgesic actions (e.g., GABAA, NMDA, and Nav1.2 channels). Pilot studies in rats have shown that these compounds produce analgesic and anesthetic effects and can also be used for euthanasia at higher doses. This study hypothesizes that methyl salicylate and L-carvone produce analgesia and anesthesia in sheep and can also be used as euthanasia agents. This project aims to evaluate the pharmacokinetics of methyl salicylate and L-carvone when administered intramuscularly and subcutaneously in sheep, and to measure their plasma concentrations over time. The measured values will be adapted to pharmacokinetic models that describe the respective phases of absorption, distribution, and elimination. Furthermore, to evaluate the pharmacodynamic effects of both compounds, it was initially necessary to measure the plasma concentrations of each compound to prevent motor responses to nociceptive stimuli. Analgesic efficacy will be assessed using an electrical stimulator, and the observed behavioral responses will be correlated with the plasma concentrations of the administered compounds. (AU)