Evaluating the use of a butorphanol-azaperone-medetomidine fixed-dose combination for standing sedation in African elephants (Loxodonta africana)
This study investigated the use of a fixed-dose combination of 30 mg/ml butorphanol, 12 mg/ml azaperone, and 12 mg/ml medetomidine for the standing sedation of captive African elephants (Loxodonta africana). In total, seven females (mean age 19.6 yr; range 6–31 yr) and six males (mean age 33.5 yr; range 9–35 yr) were sedated. The estimated dose was 0.0005 6 0.0001 ml/kg and 0.006 6 0.001 ml/cm shoulder height, which resulted in a dose of 0.016 6 0.002 mg/kg or 0.19 6 0.04 mg/cm shoulder height butorphanol, 0.006 6 0.0008 mg/kg or 0.076 6 0.015 mg/cm shoulder height azaperone, and 0.006 6 0.0008 mg/kg or 0.076 6 0.015 mg/cm medetomidine. First signs of sedation were observed within 3–10 min (mean 6 6 2 min) after darting, and monitoring of the animals started on average at 24 6 9 min after darting. No bradycardia was observed in any of the elephants (mean heart rate 40.0 6 6.55 beats/min), although all the animals were mildly hypotensive (mean blood pressure 118.5/86 [94.5]). Rectal temperatures fell within acceptable ranges, and respiratory parameters were stable in all the animals throughout sedation and fell within the standard ranges reported for conscious, standing elephants. Only one elephant had clinically significant hypoxemia characterized by a partial pressure of oxygen (PaO2), 60 mm Hg. This elephant was also hypercapnic (PaCO2 > 50 mm Hg), although pH and peripheral capillary oxygen saturation fell within acceptable ranges. None of the elephants reacted to moderately painful stimuli while sedated. The combination was reversed with intramuscular injections of naltrexone (1 mg for every 1 mg butorphanol) and atipamezole (5 mg for every 1 mg medetomidine). Recovery was smooth and calm in all the animals. Time from injection of the reversals until the first signs of recovery was 4.6 6 2.01 min (range 1–8 min).