Anesthesia in foals

Anesthetic drugs provide unconsciousness, analgesia and muscle relaxation for the purposes of carrying out procedures; however, these drugs may have adverse effects that can increase the risk of morbidity and mortality. Neonatal foals are physiologically different from adults due to the immaturity of their body systems, resulting in altered pharmacokinetics and pharmacodynamics of anesthetic drugs. Consequently, anesthetic and analgesic techniques should be adapted to the developmental stage and the specific needs and characteristics of each foal. In the first days and weeks of life, foals transition to the extrauterine environment and undergo major physiological changes that affect almost all systems and functions, including circulation, respiration, oxygen and nutrient delivery and consumption, central and peripheral neuronal activity, thermoregulation and immune system activity. Administering safe anesthesia in foals requires a thorough understanding of these changes. A complete history, physical examination and clinical pathology data are essential prior to developing any protocol for sedation, anesthesia and analgesia, to identify specific problems that may affect the anesthetic procedure. In addition, foal anesthesia requires comprehensive monitoring of anesthetic parameters, as rapid changes requiring urgent intervention are common.