Intraoperative opioid-sparing effect of a quadratus lumborum block using low-concentration bupivacaine and dexmedetomidine in cats undergoing ovariohysterectomy.

ObjectivesThis study aimed to evaluate the intraoperative opioid-sparing effect of quadratus lumborum block (QLB) using low-concentration bupivacaine combined with dexmedetomidine in cats undergoing ovariohysterectomy.MethodsA total of 28 cats scheduled for ovariohysterectomy and classified as American Society of Anaesthesiologists status I were enrolled and randomly allocated to either a bupivacaine (0.125%) and saline (BS) or bupivacaine (0.125%) and dexmedetomidine (1 µg/kg) (BD) group. The cats underwent ultrasound-guided QLB in sternal recumbency using the allocated solution. If heart rate or mean arterial pressure increased by 20% or more from baseline during surgery, fentanyl (2 µg/kg IV) was administered as rescue analgesia. Postoperative pain was assessed 1, 2, 3, 6 and 12 h after extubation using the Short-Form UNESP-Botucatu Multidimensional Composite Pain Scale. Buprenorphine (0.02 mg/kg IM) was administered if the pain score was 4/12 or higher.ResultsThe cumulative intraoperative dose of fentanyl was significantly lower in the BD group (1 µg/kg [range 0-6]) than in the BS group (2 µg/kg [range 0-8];