Total intravenous anaesthesia in adult mules

Objective To design an effective intravenous (IV) anaesthetic combination for field use in mules. Study design Descriptive study. Animals Six healthy adult mules. Methods Xylazine 1.3 mg kg(-1) was administered IV and the quality of sedation was recorded. Anaesthesia was induced with 0.03 mg kg(-1) diazepam and 2.2 mg kg(-1) ketamine IV. Times to sternal recumbency, lateral recumbency and standing were recorded. Heart rate (HR), respiratory rate (f(R)), rectal temperature and haematological parameters were recorded at baseline and at 5, 15 and 45 minutes post-administration. Additionally, levels of antinociception according to responses to a pin prick test, and the quality of muscle relaxation and recovery were scored. Results Times (mean +/- standard deviation) to sternal and lateral recumbency were 1.3 +/- 1.3 minutes and 1.8 +/- 1.3 minutes, respectively, with hypertonicity of the pelvic limbs. Standing ataxia and normal gait were seen at 25.5 +/- 19.0 minutes and 32.8 +/- 7.9 minutes, respectively. Five minutes after induction of anaesthesia, the quality of antinociception was judged to be good to excellent (0 +/- 1 on a scale of 0-3), muscle relaxation of the jaw incomplete (2 +/- 1 on a scale of 1-4) and quality of recovery was very good to excellent (2 +/- 1 on a scale of 1-5). The duration of anaesthesia was only 15.3 +/- 1.6 minutes. Significant changes were observed only in HR at 15 minutes and f(R) at 5 minutes. Changes in rectal temperature and haematological parameters following anaesthesia were non-significant. Conclusions and clinical relevance The combination of xylazine-diazepam-ketamine provides effective short-term anaesthesia in mules under field conditions.