Use of supplemental intravenous anaesthesia / analgesia in horses

General anaesthesia in horses is associated with a significant risk of both morbidity and mortality. One major factor contributing to this is the marked cardiopulmonary depression that occurs in this species in association with the use of volatile anaesthetic agents. Attempts to minimise the required volatile concentration for the maintenance of unconsciousness by administering additional injectable agents may have beneficial effects on the outcome for the animal. This article describes the characteristics of the agents commonly used for supplemental intravenous anaesthesia/analgesia (SIVA), and highlights the key points that must be taken into consideration when undertaking the concurrent administration of these drugs