Twelve adult rhebok (Pelea capreolus) were immobilized using a combination of 0.4 mg/kg
xylazine and either 0.01 mg/kg of
carfentanil (n = 6) or 0.01 mg/kg
etorphine (n = 6), delivered i.m. using a remote injection system. Induction and recovery times, heart rate, respiratory rate, rectal temperature, oxygen saturation, end-tidal CO2 (ETCO2),
anesthetic depth, indirect blood pressure, and arterial blood
gases were recorded. Rhebok were not intubated but nasal
oxygen was administered. Forty minutes after induction,
anesthesia was antagonized with
naltrexone and
yohimbine. Mean initial heart rate was significantly higher in the
carfentanil group than in the
etorphine group. Mean initial oxygen saturation was consistent with
hypoxia in both the
carfentanil group and the
etorphine group. In both groups, arterial pH decreased and partial pressure of
carbon dioxide increased during the first 15 min of
anesthesia, and values were similar in both groups. These findings were consistent with
respiratory acidosis and decreased ventilation. Values for respiratory rate, temperature, oxygen saturation, ETCO2, and blood pressure were similar for both groups at all time periods. During the first 5 min of
anesthesia, rhebok in the
carfentanil group were more responsive to stimuli than rhebok in the
etorphine group. After administration of antagonists, time to first arousal was significantly shorter in the
etorphine group than in the
carfentanil group. Although cardiopulmonary values were similar for the two groups, rhebok in the
carfentanil group were at a comparatively lighter plane of
anesthesia, and some individuals in this group required additional manual and chemical restraint for medical procedures to be performed. In conclusion, for captive adult rhebok, 0.01 mg/kg of
etorphine and 0.4 mg/kg of
xylazine are recommended over 0.01 mg/kg
carfentanil and 0.4 mg/kg
xylazine because of qualitatively better
anesthetic episodes and shorter recovery times.