Comparison of the effect of intratesticular lidocaine/bupivacaine vs. saline placebo on pain scores and incision site reactions in dogs undergoing routine castration.

Post-operative pain scores and incision site reactions were compared in healthy dogs undergoing routine castration at a county animal shelter and assigned to two treatment groups, namely: (1) lidocaine/bupivacaine (1mg/kg lidocaine+1mg/kg bupivacaine mixture; n=17), or (2) placebo (0.9% saline; n=16), administered via intratesticular injection. Dogs were injected with an equivalent volume of solution based on bodyweight. Premedication, induction and anesthetic maintenance protocols were identical in all animals. Pain scores were assessed at 15min, 60min, 120min and 24h post-recovery from anesthesia. Surgical site evaluation based on swelling and bruising was evaluated at 24h. The addition of lidocaine/bupivacaine did not impact pain scores compared to the saline placebo (P>0.05). Incision site reactions were statistically similar between the two groups.