Effects of Butorphanol on Respiration in White Rhinoceros (Ceratotherium simum) Immobilized with Etorphine-Azaperone.

This article reports on respiratory function in white rhinoceros (Ceratotherium simum) immobilized with etorphine-azaperone and the changes induced by butorphanol administration as part of a multifaceted crossover study that also investigated the effects of etorphine or etorphine-butorphanol treatments. Six male white rhinoceros underwent two immobilizations by using 1) etorphine-azaperone and 2) etorphine-azaperone-butorphanol. Starting 10 min after recumbency, arterial blood gases, limb muscle tremors, expired minute ventilation, and respiratory rate were evaluated at 5-min intervals for 25 min. Alveolar to arterial oxygen gradient, expected respiratory minute volume, oxygen consumption, and carbon dioxide production were calculated. Etorphine-azaperone administration resulted in hypoxemia and hypercapnia, with increases in alveolar to arterial oxygen gradient, oxygen consumption, and carbon dioxide production, and a decrease in expired minute ventilation. Muscle tremors were also observed. Intravenous butorphanol administration in etorphine-azaperone-immobilized white rhinoceros resulted in less hypoxemia and hypercapnia; a decrease in oxygen consumption, carbon dioxide production, and expired minute ventilation; and no change in the alveolar to arterial oxygen gradient and rate of breathing. We show that the immobilization of white rhinoceros with etorphine-azaperone results in hypoxemia and hypercapnia and that the subsequent intravenous administration of butorphanol improves both arterial blood oxygen and carbon dioxide partial pressures.

Effect of Azaperone on Induction Times in Etorphine-Immobilized White Rhinoceros (Ceratotherium simum).

We describe induction time in six white rhinoceros (Ceratotherium simum) when they received etorphine intramuscularly (IM) or etorphine plus azaperone IM. The median induction time was reduced from 8.9 min for etorphine alone to 6.25 min with azaperone; however, there was no difference in immobilization quality between treatments.

Evaluation of Physiological Parameters and Effectiveness of an Immobilization Protocol Using Etorphine, Azaperone, and Butorphanol in Free-Ranging Warthogs (Phacochoerus africanus).

Twenty free-ranging warthogs (Phacochoerus africanus) in the Kruger National Park, South Africa, were immobilized with a combination of etorphine (0.039 ± 0.005 mg/kg) and azaperone (0.44 ± 0.06 mg/kg) administered intramuscularly by dart. Butorphanol (1 mg per mg etorphine) was administered intravenously at t = 5 min. A standardized scoring system was used to record induction, immobilization and recovery characteristics. Physiological parameters were recorded at 5 min intervals and an arterial sample collected for blood gas analyses every 15 min. At 45 min after butorphanol administration, immobilization was partially reversed by administering naltrexone (40x etorphine dose in mg) intravenously. Overall, induction quality was good, with the mean time to safe handling 5.9 ± 1.4 min. The majority of immobilization scores (54%) over the entire monitoring period (40 min) were at level 3, consistent with a light plane in which palpebral and laryngeal reflexes were still present but the animal could be safely handled. Overall mean heart rate was 94.7 ± 15.3 beats per min, mean respiratory rate was 14.7 ± 9.8 breaths per min, and the mean rectal temperature was 38.5 ± 1.0°C. Significant hypoxia (overall mean oxygen arterial partial pressure 38.8 ± 8.4 mmHg), hypercapnia (mean carbon dioxide arterial partial pressure 63.3 ± 7.8 mmHg), and acidosis (mean pH 7.28 ± 0.04) were observed in immobilized warthogs. Following antagonist administration, warthogs were standing within 1.0 ± 0.4 min, with the majority of recoveries scored as excellent. The drug combination proved to be effective in the immobilization of free-ranging warthogs with rapid induction and recovery, but with significant cardio-respiratory changes. Therefore, this drug combination may be useful when rapid immobilization and recovery are indicated, but should be used cautiously in compromised warthogs.