Tiletamine-zolazepam anesthesia in North American river otters (Lutra canadensis) and its partial antagonism with flumazenil.

North American river otters (Lutra canadensis) were anesthetized with tiletamine-zolazepam or tiletamine-zolazepam-flumazenil combinations in cooperation with the North Carolina Wildlife Resources Commission Otter Restoration Project for evaluation of physiologic changes during anesthesia. Sixteen otters received tiletamine-zolazepam (4 mg/kg combined, i.m.) in 1994. Induction and recovery times were recorded and physiologic data (heart rate and rhythm, respiratory rate, rectal temperature, relative oxyhemoglobin saturation, and mean arterial blood pressure) were collected at 5-min intervals. Respiratory depression developed initially in all otters, and median relative oxyhemoglobin saturation remained below 90% for the first 15 min of anesthesia. Anesthetic induction with tiletamine-zolazepam was rapid and smooth, but recovery was prolonged (median = 89 min) and characterized by persistent head motion. In 1995, flumazenil was evaluated as a partial antagonist for tiletamine-zolazepam anesthesia in otters. Sixteen otters were anesthetized with tiletamine-zolazepam (4 mg/kg combined, i.m.) and given flumazenil (1 mg per 25 mg of zolazepam) after 20 min. Flumazenil markedly shortened recovery time in all otters anesthetized with tiletamine-zolazepam (median = 65 min) with no adverse effects.