A preliminary comparison of epidural lidocaine and xylazine during total intravenous anaesthesia in Iranian fat-tailed sheep.

ABSTRACT

The effects of total intravenous anaesthesia using diazepam-ketamine (D-K) mixture in combination with epidural lidocaine or xylazine were studied in 17 healthy, Iranian fat-tailed sheep undergoing hindlimb orthopaedic surgery. All sheep were given diazepam (0.4 mg/kg) and ketamine (4 mg/kg) as induction agents. Following endotracheal intubation and administration of oxygen, the animal received lidocaine (2%, 0.2 ml/kg = 4 mg/kg) or xylazine (0.08 mg/kg, diluted in 0.9% NaCl to a volume of 0.2 ml/kg) epidurally. Anaesthesia was maintained for 174.2 +/- 7.8 minutes by intermittent injection of D-K (2.5 mg/ml and 25 mg/ml, respectively). This drug combination provided satisfactory anaesthesia for more than 2.5 hours. The quality of recovery was good. Our results demonstrate that the combination of total intravenous anaesthesia (D-K) and epidural analgesia (lidocaine or xylazine) provides a suitable technique for hindlimb orthopaedic surgery in sheep. Epidural administration of lidocaine or xylazine provided effective analgesia and significantly decreased the dose of D-K required to maintain anaesthesia. Further studies would be required to determine details of cardiopulmonary effects of D-K infusion.