Effetto analgesico della somministrazione in infusione continua di lidocaina cloridrato nella chirurgia perineale del cane

Aim of the study was to evaluate the pre-emptive analgesic effect obtained by systemic continuous infusion of lidocaine (LID) in comparison with those obtained by systemic continuous infusion of fentanyl (FEN) during and after canine perineal surgery. Twelve male dogs undergoing perineal surgery were preanaesthetised with acepromazine (0.03 mg kg-1 IM), induced with propofol (4-6 mg kg-1 IV), and maintained with isoflurane in 100% oxygen. Fifteen minutes before perineal surgery, perineal herniorrhaphy or adenoma (Ø 3-5 cm) excission, all the animals were randomly assigned to receive a bolus followed by a systemic continuous infusion: lidocaine (1 mg kg-1 IV + 0.05 mg kg-1min-1 IV) in LID group(n=6) or fentanyl (5 mcg kg-1 IV + 0.05 mcg kg-1min-1 IV) in FEN group (n=6). Subjective pain score system, modified by Smith, was used for evaluation of pain at 0.5, 1, 2, 3, 4, 8, 16, and 24 hours after extubation (T0). All dogs showing pain score ≥ 9 (maximum=24) were treated with a rescue analgesic drug (buprenorphine 10 mcg kg-1 ) and excluded from further analysis. Physiological parameters during anaesthesia (HR, RR, NIBP, T°, SpO2, ETCO2, ECG) and differences in pain scores in groups were analyzed using ANOVA, t test (P<0.05) and Wilcoxon’s rank-sum test. Results: there was a significantly higher incidence of treatment failure in FEN group (83,3%) than in LID group (0%). After four hours, post-operative pain scores in LID group were significantly lower than those in FEN group. Monitored parameters during anaesthesia did not show significant differences between groups. Systemic intra-operative lidocaine provides better analgesia than fentanyl in canine post-perineal surgery, involving its potential role in pre-emptive and post-operative analgesia.