Neurology Resident Ontario Veterinary College Guelph, Ontario, Canada
Abstract: Background– Lidocaine reduces post-operative pain, and shows anti-inflammatory properties through reduction of interleukin-6 (IL-6) levels in humans undergoing spinal surgery. The analgesic effects of lidocaine after spinal surgery have not been studied in dogs. Objectives– To evaluate the effects of intra-operative intravenous (IV) lidocaine continuous rate infusion (CRI) on post-operative pain and IL-6 levels in dogs undergoing thoracolumbar hemilaminectomy. Animals– 40 client-owned dogs undergoing hemilaminectomy for intervertebral disc extrusion (IVDE). Methods– Prospective, randomized, blinded, controlled study. Dogs were anesthetized with a standardized protocol that included fentanyl CRI for intra- and post-operative analgesia. Additionally, dogs received either lidocaine CRI at 100 mcg/kg/min or NaCl 0.9% (control) intraoperatively. Pain scores were assessed on presentation, 0-, 2-, 6-, 12-, and 24-hours post-anesthesia recovery via the short form of the Glasgow Composite Measure Pain Scale (CMPS-SF). IL-6 levels were assessed on presentation, 0-, 6-, and 48-hours post-operatively. Results– Lidocaine group had significantly lower pain scores compared to control group at 0-hour post-anesthesia (p=0.023) with no significant differences between groups at other times. There were no significant differences in IL-6 levels between groups and no correlation between IL-6 values and post-operative pain scores. Conclusion and clinical importance– Intra-operative IV lidocaine administration is associated with a lower CMPS-SF score during the immediate post-operatively period with no change in IL-6 levels 48 hours post-operatively when compared to dogs receiving only opioids. Intra-operative IV lidocaine CRI should be considered in the anesthetic protocol for thoracolumbar hemilaminectomy in dogs although its benefits are not mediated by an IL-6 reduction.
