Abstract

Alfaxalone is a neurosteroid drug that interacts with GABA_A receptors in the brain. It has the potential to improve the efficacy of existing alpha-2-adrenergic agonist-based wildlife anesthesia combinations but there are few studies of its use in wild mammals.^1,2 The objective of this study was to determine the efficacy and safety of a medetomidine-azaperone-alfaxalone (MAA) drug combination used to anesthetize captive white-tailed deer (Odocoileus virginianus). Eight captive, adult, white-tailed deer were hand-injected intramuscularly with 0.15 mg/kg medetomidine, 0.2 mg/kg azaperone, and 0.5 mg/kg alfaxalone. Once anesthetized, deer were maintained in lateral recumbency and monitored for 60 minutes. Heart and respiratory rate; rectal temperature; and direct systolic, mean, and diastolic blood pressures were recorded every five minutes. Blood gas analysis was done on arterial blood every 15 minutes. The level of sedation and quality of recovery from anesthesia after reversal with 0.75 mg/kg of atipamezole were scored. Analysis of variance and descriptive statistics (significance of p<0.05) was used to analyze data. Induction (time to lateral recumbency, 7.1±2.4 minutes [mean ± SD]) and recovery times (time to standing, 9.1±3.1 minutes) were comparable to current medetomidine-based combinations in white-tailed deer.^3-5 Cardiopulmonary effects observed at 15-minutes post-injection 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). Blood pressure was in normotensive range (mean BP 99±8 mm Hg) and recovery was consistently smooth with minimal struggling or ataxia. MAA produced a satisfactory and safe level of deep sedation for handling and minor procedures in captive white-tailed deer.

Acknowledgments

The authors thank Dr. Adam Hering and Ms. Mary von der Porten for assistance with animal handling and data collection. This project was funded by the University of Calgary Clinical Research Fund and a final-year student investigative medicine grant.

Literature Cited

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