Compared to etorphine-azaperone, the ketamine-butorphanol-medetomidine combination is also effective at immobilizing zebra (Equus zebra)

Objective To compare immobilization efficacy of a nonpotent opioid drug combination, ketamine-butorphanol-medetomidine (KBM) to the preferred etorphine-azaperone (EA) combination in zebras. Study design Randomized crossover trial. Animals A group of ten adult zebra (six females and four male). Methods KBM and EA were administered once to the zebras in random order by dart, 3 weeks apart. Once a zebra was recumbent and instrumentedw, physiological parameters were measured and recorded at 5-minute intervals until 20 minutes. Antagonist drugs were administered at 25 minutes. KBM was antagonised using atipamezole (7.5 mg mg(-1) medetomidine dose) and naltrexone (2 mg mg(-1) butorphanol dose). EA was antagonized using naltrexone (20 mg mg(-1) etorphine dose). Induction and recovery (following antagonist administration) times were recorded. Physiological parameters, including invasive blood pressure and blood gas analysis, were compared between combinations using a general linear mixed model. Data are reported as mean +/- standard deviation or median (interquartile range). Results The doses of KBM and EA administered were 3.30 +/- 0.18, 0.40 +/- 0.02 and 0.16 +/- 0.01 mg kg(-1); and 0.02 +/- 0.001 and 0.20 +/- 0.01 mg kg(-1), respectively. KBM and EA induction times were 420 (282-564) and 240 (204-294) seconds, respectively (p = 0.03). Zebras remained recumbent throughout the study procedures. Systolic blood pressure (226 +/- 42 and 167 +/- 42 mmHg) and oxygen partial pressure (64 +/- 12 and 47 +/- 13 mmHg) were higher for KBM compared to EA (p < 0.01). Recovery time, after administering antagonists, was 92 (34-1337) and 26 (22-32) seconds for KBM and EA, respectively (p = 0.03). Conclusions and clinical relevance Compared to EA, KBM also immobilized zebras effectively. Systemic hypertension and moderate hypoxaemia are clinical concerns of KBM and severe hypoxaemia is a concern of EA. This occurrence of hypoxaemia highlights the importance of oxygen administration during immobilization.