Comparative cardiopulmonary effects of carfentanil-xylazine and medetomidine-ketamine used for immobilization of mule deer and mule deer/white-taileddeer hybrids

Three mule deer and 4 mule deer/white-tailed deer hybrids were immobilized in a crossover study with carfentanil (10 mu g/kg) + xylazine (0.3 mg/kg) ( CX), and medetomidine (100 mu g/kg) + ketamine (2.5 mg/kg) (MK). The deer w ere maintained in left lateral recumbency for 1 h with each combination. De er were immobilized with MK in 230 +/- 68 s (mean +/- SD) and with CX in 28 2 +/- 83 seconds. Systolic, mean and diastolic arterial pressure were signi ficantly higher with MK. Heart rate, PaO2, PaCO2, pH, and base excess were not significantly different between treatments. Base excess and pH increase d significantly over time with both treatments. Both treatments produced hy poventilation (PaCO2 > 50 mmHg) and hypoxemia (PaO2 < 60 mmHg). PaO2 increa sed significantly over time with CX. Body temperature was significantly (P < 0.05) higher with CX compared to MK. Ventricular premature contractions, atrial premature contractions, and a junctional escape rhythm were noted du ring CX immobilization. No arrhythmias were noted during MK immobilization. Quality of immobilization was superior with MK, with no observed movement present for the 60 min of immobilization. Movement of the head and limbs oc curred in 4 animals immobilized with CX. The major complication observed wi th both of these treatments was hypoxemia, and supplemental inspired oxygen is recommended during immobilization. Hyperthermia can further complicate immobilization with CX, reinforcing the need for supplemental oxygen.