FIELD ANESTHESIA IN THE NORTH-AMERICAN RIVER OTTER (LUTRA-CANADENSIS)

During winter 1992, 48 North American river otters (Lutra canadensis) were anesthetized in cooperation with an otter restoration program adm inistered by the North Carolina Wildlife Resources Commission. Three a nesthetic protocols were evaluated: ketamine, ketamine/midazolam, and isoflurane. Heart rate and rhythm, respiratory rate, rectal temperatur e, oxyhemoglobin saturation, and systolic, diastolic, and mean arteria l blood pressures were monitored every 5 min during anesthesia. Anesth esia intervals (induction time, total anesthesia time, recovery time, and total immobilization time) were recorded. Hematologic and serum bi ochemical analyses were performed on all otters. Ketamine anesthesia ( 10 mg/kg) was adequate in most otters, but anesthesia time was short ( median = 17.6 min), and 15/16 otters exhibited one or more of the foll owing: tachycardia, bradycardia, tachypnea, bradypnea, relative hypoxe mia, hyperthermia, random limb movement, and poor myorelaxation. The c ombination of midazolam (0.25 mg/kg) with ketamine (10 mg/kg) in the r iver otter produced fewer anesthetic-related complications, longer ane sthesia time (median = 26 min), and greater muscle relaxation than did ketamine alone. Most otters anesthetized with isoflurane were free of cardiopulmonary complications, but the animals struggled vigorously d uring placement of the facemask for induction.