EFFICACY AND SAFETY OF A MEDETOMIDINE-AZAPERONE-ALFAXALONE COMBINATION IN CAPTIVE WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS).

Alfaxalone is a neurosteroid that interacts with gamma-aminobutyric type A receptors to produce central nervous system depression and muscle relaxation. The effects of alfaxalone vary from sedation to general anesthesia. Alfaxalone is synergistic with other tranquilizers and sedatives and therefore has the potential to improve existing alpha-2 adrenergic agonist-based combinations used for wildlife immobilization. The objective of this study was to determine the efficacy and cardiopulmonary effects of a medetomidine-azaperone-alfaxalone (MAA) combination in captive white-tailed deer (Odocoileus virginianus). Eight captive white-tailed deer were restrained in a drop-floor chute; hand injected i.m. with 0.15 mg/kg medetomidine, 0.2 mg/kg azaperone, and 0.5 mg/kg alfaxalone; and released into a small enclosure for observation. The deer were maintained in lateral recumbency for a total time from postinjection (PI) of the drug of 60 min. At 60 min PI, atipamezole was administered i.m. at five times the medetomidine dose. Heart rate, respiratory rate, rectal temperature, and direct systolic, mean, and diastolic arterial blood pressures were recorded every 5 min. Arterial blood samples were taken every 15 min for blood gas analysis. Level of sedation and quality of recovery were scored. Statistical analysis was performed using analysis of variance and descriptive statistics with a significance level of P < 0.05. Induction (time to lateral recumbency, 7.1 ± 2.4 min (mean ± SD) and recovery times (time to standing, 9.1 ± 3.1 min) were comparable to currently used medetomidine-based combinations in white-tailed deer. Major cardiopulmonary effects observed (values reported are 15 min PI of immobilizing drugs) were hypoxemia (PaO2, 54 ± 9 mm Hg), hypoventilation (PaCO2, 55 ± 3 mm Hg), and mixed acid-base disturbances (pH, 7.22 ± 0.04). No adverse effects were observed after recovery from anesthesia. MAA produced a satisfactory level of deep sedation for safe handling and minor procedures in captive white-tailed deer.