Morbidity, mortality, and risk of general anesthesia in horses.

General anesthesia in horses carries an increased risk of morbidity and mortality compared with other species. In recent years the number and complexity of epidemiologic studies in equine anesthesia has increased. The ability to interpret such studies and understand epidemiologic terminology is vital for veterinarians for them to make potential improvements to their anesthetic practice and to allow them to communicate effectively the findings of such studies to colleagues and owners. This article provides the equine clinician with a basic understanding of the methodologies that can be used in observational epidemiologic studies, and reviews the literature on equine anesthetic morbidity, mortality, and risk.