Comparison of three methods for control of postoperative pain in dogs after total ear canal ablation with lateral bulla osteotomy

Abstract

This prospective study compared three methods of postoperative pain control in dogs undergoing total ear canal ablation with lateral bulla osteotomy. The hypothesis was that systemic opioids in conjunction with preoperative local nerve blocks would provide superior postoperative analgesia. Thirty-one dogs with chronic otitis externa were included in the study. Nineteen dogs were cocker spaniels, with 10 other breeds represented. Ten dogs had previous ear surgery. Dogs were randomly assigned to three analgesic protocols: systemic opioids alone (10), systemic opioids with bupivacaine splash block (I 1), and systemic opioids with preoperative local bupivacaine nerve blocks (10). Twenty-one dogs had bilateral ear ablation and 10 had unilateral ablation. Pain was assessed preoperatively, at extubation, 2 hours post-extubation and 1 day postoperatively by a single observer blinded to the analgesic protocol used. Pain scores were not significantly different within or between groups, nor did unilateral versus bilateral ablation have a significant effect on the score. Mean scores were less than 3 (scale 1-5) for all groups at all observation times. Rough recoveries were noted in 30% of group I dogs, 0% of group II, and 20% of group III. Ninety-four percent of dogs were moderately to heavily sedated at the time of extubation. Sixty percent of group III dogs remained moderately to heavily sedated 2 hours post-extubation. Temperature, pulse rate, respiratory rate, and postoperative change in serum cortisol levels were not significantly different between groups. Postoperative increase in serum glucose was significantly higher in groups I and III compared to preoperative levels. Sixteen percent of dogs required additional postoperative analgesia or tranquilization, as determined by the anesthetist; 1 dog in group I, 2 in group 11, and 4 in group III. Each of the three analgesic protocols were concluded to be satisfactory for postoperative pain relief in dogs having total ear canal ablation.