Improvement of arterial oxygenation in free-ranging moose (Alces alces) immobilized with etorphine-acepromazine-xylazine

Background: The effect of intranasal oxygen and/or early reversal of xylazine with atipamezole on arterial oxygenation in free-ranging moose (Alces alces) immobilized with etorphine-acepromazine-xylazine with a cross-sectional clinical study on 33 adult moose was evaluated.Moose were darted from a helicopter with 3.37 mg etorphine, 15 mg acepromazine and 75 mg xylazine. Intranasal oxygen at a flow rate of 4 L/min and/or early reversal of xylazine with 7.5 mg atipamezole to improve oxygenation was evaluated, using four treatment regimens; intranasal oxygen (n = 10), atipamezole intramuscularly (n = 6), atipamezole intravenously (n = 10), or a combination of atipamezole intravenously and intranasal oxygen (n = 7). Arterial blood was collected 7-30 minutes (min) after darting, and again 15 min after institution of treatment and immediately analyzed using an i-STAT (R) 1 Portable Clinical Analyzer.Results: Before treatment the mean +/- SD (range) partial pressure of arterial oxygen (P-aO2) was 62 +/- 17 (26-99) mmHg. Twenty-six animals had a P-aO2 < 80 mmHg. Ten had a P-aO2 of 40-60 mmHg and three animals had a P-aO2 < 40 mmHg. Intranasal oxygen and intravenous administration of atipamezole significantly increased the mean P-aO2, as did the combination of the two. In contrast, atipamezole administered intramuscularly at the evaluated dose had no significant effect on arterial oxygenation.Conclusions: This study shows that intranasal oxygen effectively improved arterial oxygenation in immobilized moose, and that early intravenous reversal of the sedative component, in this case xylazine, in an opioid-based immobilization drug-protocol significantly improves arterial oxygenation.