The Effect of Xylazine Premedication on the Dose and Quality of Anesthesia Induction with Alfaxalone in Goats

Abstract

Goats have been used as animal models in research and are increasingly kept as companion animals. However, information about effective anesthetic drugs is scarce in this species. The objective of this study was to evaluate the effect of xylazine premedication on alfaxalone induction. Twelve clinically healthy goats weighing 18.5 ± 2 kg were randomly assigned to two groups. Induction was performed with alfaxalone alone intravenously (ALF group) or with xylazine premedication before alfaxalone administration (XYL-ALF group). The quality of induction was scored, induction doses of alfaxalone were determined, and cardiorespiratory parameters and nociceptive thresholds were measured before any treatment(s) (baseline) and at 5, 15, 25 and 35 min after alfaxalone administration. The mean dose of alfaxalone required for induction in the ALF group was greater than that in the XYL-ALF group (p < 0.001). There were no significant changes in diastolic arterial pressure (DAP), mean arterial pressure (MAP) or systolic arterial pressure (SAP) compared to baseline in either group, while hemoglobin oxygen saturation (SpO₂) was lower from 5 to 25 min (p < 0.5) in the XYL-ALF group. The nociceptive threshold was significantly higher at 5 min in the XYL-ALF group than in the ALF group (p = 0.0417). Xylazine premedication reduced the required dose of alfaxalone for anesthetic induction and produced better antinociception than alfaxalone alone. In addition, the combination of xylazine and alfaxalone allowed for successful induction; however, oxygen supplementation is necessary to counteract xylazine-associated hypoxemia.

Keywords: alfaxalone; cardiorespiratory parameters; goats; induction; xylazine.

Figure 1

Study timeline illustrating the time of anesthetic induction with IV alfaxalone alone (ALF group) (n = 6) and with alfaxalone following IV xylazine administration (XYL-ALF) (n = 6). The data collection time points were at baseline and at 5, 15, 25 and 35 min after alfaxalone. The pedal withdrawal reflex and end tidal carbon dioxide (P_E’ CO₂) were recorded only at 5 min after alfaxalone administration (black arrows).