Effect of Constant Rate Infusion of Xylazine & Xylazine Morphine Combination on Sedation, Analgesia and Ataxia in Horses |Biomedgrid

In standing horses, notable sedation and analgesia may be attained by using α2-agonists/opioids combinations relative to α2-agonists alone. Therefore, this study aimed to evaluate the effect of a constant rate infusion (CRI) of xylazine (XYL) alone or in combination with morphine (XYL/ MOR) on sedation, analgesia and ataxia in horses. Five adult healthy horses were assigned to receive two sedative protocols at one week interval as follows, XYL (0.55 mg/kg of xylazine IV directly followed by xylazine CRI of 1.08 mg/kg/hour followed later by saline bolus and a CRI of saline) and XYL/MOR (0.55 mg/kg of xylazine IV directly followed by xylazine CRI of 0.66mg/kg/hour followed later by morphine 0.15 mg/kg, IV and morphine CRI of 0.1 mg/kg/hour). The effect of both protocols on sedation, analgesia and ataxia was assessed following xylazine administration by 10, 15 minutes and later at 15 minutes interval for 120 minutes during infusion of the tested combinations and every 15 minutes for 60 minutes after cessation of infusion. Relative to baseline, significant changes in sedative and analgesic scores were detected for 120 minutes with significant ataxia for only 15 minutes following both treatments. Addition of morphine to xylazine produced significantly higher sedation scores compared to xylazine alone for 120 minutes with slightly higher analgesic scores at some time points without significantly different ataxia scores in between. In conclusion, xylazine/morphine protocol had a superior sedative effect compared to xylazine alone consequently it might be better alternative to xylazine protocol during standing interventions in horses.