Evaluation of sedation by intramuscular administration of dexmedetomidine, midazolam, butorphanol in king penguins (Aptenodytes patagonicus) under managed care
Abstract
King penguins (Aptenodytes patagonicus) are the second largest species of Sphenisciformes. Although it is not uncommon to manually restrain smaller penguin species for induction with inhalant anesthesia, doing so in larger species presents challenges. Therefore, this prospective study aimed to establish a safe, reliable, and fully reversible injectable sedation protocol to facilitate minimally invasive procedures in king penguins. Nine apparently healthy king penguins were sedated with 0.02 mg/kg dexmedetomidine, 1 mg/kg butorphanol, and 1 mg/kg midazolam IM. Each received an induction and recovery score (1–4), as well as sedation scores every 10 min. Additionally, an immobilization score was assigned at four milestones: attaching monitoring equipment and attempted intubation, physical examination, venipuncture, and two-view whole body radiographs. After completion of milestones, individuals were reversed with 0.2 mg/kg atipamezole, 2 mg/kg naltrexone, and 0.01 mg/kg flumazenil IM. As ordinal variables, descriptive statistics for induction, recovery, sedation, and immobilization scores as well as time values are reported as median (range). This protocol achieved an adequate sedation plane to complete all milestones except intubation in all birds. The induction time was 16 (15–21) min and recovery time was 11 (8–24) min. Vital parameters remained stable and complete blood counts and biochemical panels were unremarkable on all birds. Regurgitation was observed in six out of nine birds (mild watery fluid in five, significant ingesta in one), which could suggest the need for longer fasting periods beyond 18 hours. There were no other significant adverse effects. Therefore, the combination of dexmedetomidine, butorphanol, and midazolam produces fully reversible, reliable sedation and presents an alternative option to manual restraint or inhalant anesthesia for minimally invasive procedures in apparently healthy king penguins.