RESUMO
OBJECTIVE: To compare the perioperative effects and pharmacoeconomics of peripheral nerve blocks (PNBs) versus fentanyl target-controlled infusion (fTCI) in dogs undergoing tibial plateau levelling osteotomy (TPLO). STUDY DESIGN: Randomized clinical study. ANIMALS: A total of 39 dogs undergoing unilateral TPLO. METHODS: After acepromazine and methadone, anaesthesia was induced with propofol and maintained with isoflurane. Dogs were allocated to group fTCI [target plasma concentration (TPC) 1 ng mL-1] or group PNB (nerve stimulator-guided femoral-sciatic block using 0.2 and 0.1 mL kg-1 of levobupivacaine 0.5%, respectively). If nociceptive response occurred, isoflurane was increased by 0.1%, and TPC was increased by 0.5 ng mL-1 in group fTCI; a fentanyl bolus (1 µg kg-1) was administered in group PNB. During the first 24 postoperative hours, methadone (0.2 mg kg-1) was administered intramuscularly according to the Short Form Glasgow Composite Pain Scale, or if pain was equal to 5/24 or 4/20 for two consecutive assessments, or if the dog was non-weight bearing. The area under the curve (AUC) of pain scores, cumulative postoperative methadone requirement, food intake and pharmacoeconomic implications were calculated. RESULTS: Incidence of bradycardia (p = 0.025), nociceptive response to surgery (p = 0.041) and AUC of pain scores (p < 0.0001) were greater in group fTCI. Postoperatively, 16/19 (84.2%) and eight/20 (40%) dogs in groups fTCI and PNB, respectively, were given at least one dose of methadone (p = 0.0079). Food intake was greater in group PNB (p = 0.049). Although total cost was not different (p = 0.083), PNB was more cost-effective in dogs weighing >15 kg. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with group fTCI, incidence of bradycardia, nociceptive response to surgery, postoperative pain scores, cumulative methadone requirement were lower, and food intake was greater in group PNB, with an economic advantage in dogs weighing >15 kg.