Efficacy of caudal epidural injection of Xylazine-Lidocaine HCl and detomidine-lidocaine HCl in domestic horses (Equus ferus caballus)

The current study was prepared to compare the efficacy of xylazine-lidocaine HCl and detomidine-lidocaine HCl following caudal epidural injection in horses, evaluating sedation, analgesia, physiological parameters, and hemato-biochemical values. This study was applied to six healthy adult horses (300-350 kg, > 4 years of age). The horses were randomly divided into two equal groups. Group 1 (seven horses) received xylazine (0.17 mg/kg bwt) + lidocaine HCl (0.06 mg/kg bwt), while Group 2 received detomidine (0.03 mg/kg bwt) + lidocaine HCl (0.06 mg/kg bwt) via caudal epidural injection. Perineal analgesia and sedation (onset time and duration) were assessed before administration and at 15, 30, 60, 90, and 120 min post-administration. Concurrently, heart rate, respiratory rate, rectal temperature, and hemato-biochemical values were recorded. The sedative duration of detomidine was longer than that of xylazine (94 ± 0.96 vs. 85 ± 0.94 min). Both detomidine and xylazine induced complete bilateral perineal analgesia in all horses. Analgesia onset was slightly faster and duration longer in detomidine-treated horses compared to xylazine, and these values are for onset of analgesia (11.79 ± 1.15 vs. 14.46 ± 0.92 min). Significant heart rate depression was observed in Group 2, in which both white blood cell count (WBC) and packed cell volume (PCV) percentage showed significant decreases. Conclusion and Clinical Relevance: The findings of this study suggest that epidural administration of detomidine-lidocaine HCl results in more effective and longer-lasting perineal analgesia compared to xylazine-lidocaine HCl.