Sedation with xylazine and lumbosacral epidural administration of lidocaine and xylazine for umbilical surgery in calves

Objective-To determine whether anesthesia consisting of sedation induced by intramuscular administration of xylazine hydrochloride and lumbosacral ana lgesia induced by epidural administration of lidocaine and xylazine is usef ul for umbilical surgery in neonatal calves. Design-Prospective study. Animals-6 neonatal male dairy calves. Procedure-Calves were sedated with xylazine (0.1 mg/kg [0.045 mg/lb] of bod y weight, IM), and 5 minutes later a 2% solution of lidocaine (0.18 to 0.24 ml/kg [0.08 to 0.11 ml/lb]) and xylazine (0.05 mg/kg [0.022 mg/lb]) were a dministered into the lumbosacral epidural space. Calves were positioned in dorsal recumbency, and the umbilical structures were resected. Local infusi on of lidocaine, cranial to the umbilicus, was required in 5 of 6 calves to provide adequate analgesia. Xylazine sedation was reversed with tolazoline (1 mg/kg [0.45 mg/lb], IV). Results-Calves maintained adequate cardiac output and oxygen delivery throu ghout the procedure but were hypotensive. Reversal of xylazine-induced seda tion with tolazoline caused transient sinus bradycardia and sinus arrest, a ccompanied by severe systemic arterial hypotension. All calves regained a s uckle reflex within 10 minutes and were able to stand within 90 minutes. Clinical Implications-Intramuscular administration of xylazine for sedation and epidural administration of lidocaine and xylazine for analgesia failed to provide satisfactory analgesia for umbilical resection without suppleme ntal local infiltration of lidocaine. The anesthetic protocol is most usefu l when respiratory compromise or cost are concerns and the surgical procedu re can be completed in < 1 hour. Caution should be exercised when tolazolin e is administered intravenously to reverse xylazine-induced sedation in cal ves.