Comparison of postoperative effects between lidocaine infusion, meloxicam, and their combination in dogs undergoing ovariohysterectomy

Objective To compare the postoperative analgesic effects of intravenous (IV) lidocaine, meloxicam, and their combination in dogs undergoing ovariohysterectomy. Study design Prospective, randomized, double-blind, controlled clinical trial. Animals Twenty-seven dogs aged (mean +/- SD) 16.1 +/- 7.5 months and weighing 22.4 +/- 17.9 kg scheduled for ovariohysterectomy. Methods Anaesthesia was induced with propofol and maintained with isoflurane. Dogs (n = 9 in each group) were allocated to receive just prior to and during surgery one of the following regimens: M group, 0.2 mg kg(-1) IV meloxicam then a continuous rate infusion (CRI) of lactated Ringer's at 10 mL kg(-1) hour(-1); L group, a bolus of lidocaine (1 mg kg(-1) IV) then a CRI of lidocaine at 0.025 mg kg(-1) minute(-1); and M + L group, both the above meloxicam and lidocaine treatments. Pain and sedation were scored, and venous samples taken for serum cortisol and glucose measurement before and at intervals for 12 hours after anaesthesia. Pain scores were assessed using a multi-parameter subjective scoring scale (cumulative scale 0-21) by three observers. The protocol stated that dogs with a total score exceeding 9 or a sub-score above 3 in any one category would receive rescue analgesia. Sedation was scored on a scale of 0-4. Results There were no significant differences in subjective pain scores, serum cortisol, and glucose concentrations between the three groups. The highest pain score at any time was 5, and no dog required rescue analgesia. None of the three regimens caused any observable side effects during or after anaesthesia. At 1 and 2 hours after extubation dogs in group L were significantly more sedated than in the other two groups. Conclusions and Clinical relevance This study suggests that, with the scoring system used, IV lidocaine and meloxicam provide similar and adequate postoperative analgesia in healthy dogs undergoing ovariohysterectomy.