Evaluation of the efficacy of sevoflurane as a general anesthetic method for noninvasive examination of gentoo penguins (Pygoscelis papua).

This study evaluated the efficacy of sevoflurane for maintaining general anesthesia during noninvasive examinations, such as computed tomography, in gentoo penguins (Pygoscelis papua). Ten captive penguins were enrolled in a prospective crossover study and assigned to two protocols. In the S group, anesthesia was induced with intravenous alfaxalone and maintained with sevoflurane, titrated to achieve an appropriate depth for noninvasive procedures. Sevoflurane concentration, recovery times, heart rate, and blood pressure were evaluated. In the premedication with midazolam and butorphanol (MBS group), the same protocol was used following premedication with intramuscular midazolam (0.25 mg/kg) and butorphanol (0.25 mg/kg). Blood samples were collected before and after anesthesia to assess lactate, glucose, and blood gas variables. The mean maintenance concentration of sevoflurane was significantly lower in the MBS group (0.5%) than in the S group (1.0%). Time to extubation (2 vs. 4 min) and complete recovery (7 vs. 12 min) were shorter in the MBS group. In both groups, heart rate remained within physiological ranges, and blood pressure was stable. In the S group, preanesthetic lactate was significantly higher, whereas base excess, bicarbonate, and total carbon dioxide were significantly lower than in the MBS group. Overall, alfaxalone induction followed by sevoflurane maintenance provided stable anesthesia and rapid recovery. Premedication with midazolam and butorphanol offered clinical advantages, including reduced sevoflurane requirements, faster recovery, and decreased preanesthetic stress.