Subarachnoid butorphanol augments lidocaine sensory anaesthesia in calves.

To determine the efficacy and safety of subarachnoid butorphanol combined with lidocaine, six calves were studied. Each calf underwent two treatments, at least one week apart, via subarachnoid injection: (1) butorphanol (0.03 mg/kg) plus 2% lidocaine (4 mg/kg) and (2) 2% lidocaine (4 mg/kg) alone. Subarachnoid injections were performed at the lumbosacral space. Analgesia, motor block, sedation, heart rate, arterial blood pressure, respiratory rate, arterial oxygen saturation as measured by pulse oximetry, and rectal temperature were compared before and after subarachnoid administration of drugs. Subarachnoid administration of the butorphanol-lidocaine combination induced bilateral prolonged analgesia extending from the coccygeal to the T11-T13 dermatomes in the calves, with minimal sedation and severe ataxia. Cardiovascular effects were significant in both treatments: heart rate was increased, and there was a minimal decrease in arterial pressure. It was concluded that adding a small dose of butorphanol to subarachnoid lidocaine in calves is effective and safe.