Postinduction butorphanol administration alters oxygen consumption to improve blood gases in etorphine-immobilized white rhinoceros

Hypoxaemia and hypercapnia in etorphine-immobilized rhinoceros resulted from an increased [P(A-a)O2] and increased V˙O2 and V˙CO2 associated with muscle tremors. Rather than being associated with changes in V˙e, it appears that improved blood gases following butorphanol administration were a consequence of decreased V˙O2 associated with reduced muscle tremoring.