Partially Reversible Immobilization of Free-Ranging Huemul Deer (Hippocamelus bisulcus) with Medetomidine-Ketamine and Atipamezole

A combination of intramuscular medetomidine and ketamine was used to immobilize 46 free-ranging huemul deer (Hippocamelus bisulcus) with a remote drug delivery system in Chilean Patagonia for tagging and biological sampling. Captures occurred in May-October of 2005-09 between fall and early spring in the southern hemisphere. An initial dose of 6.6 mg medetomidine and 185 mg ketamine was adjusted after 17 captures to 3 mg and 200 mg, respectively, in the 29 remaining deer. Mean±SD adjusted dose was 0.042±0.012 mg/kg of medetomidine and 2.929±0.427 mg/kg of ketamine. Inductions were calm and the mean±SD time to sternal recumbency was 10.3±10.1 min. Palpebral reflex and jaw tone were present during immobilization. Atipamezole at 5 mg/mg of medetomidine was administered intramuscularly for reversal after 55.3±18.8 min procedure time. Recoveries were smooth and mean±SD time to standing was 10.2±3.3. All immobilized animals were hypoxemic by pulse oximetry (blood oxygen saturation approximately 81%). Three animals that developed apnea were resuscitated through chest compression and atipamezole administration, another regurgitated during capture, and all developed tachypnea. The combination of medetomidine-ketamine and atipamezole can be used for partially reversible immobilization of huemul, but supplemental oxygen should be administered, blood oxygenation should be monitored, and equipment for intubation and manual ventilation should be available.