Erector spinae plane block with bupivacaine contributes to intraoperative opioid sparing but provides limited postoperative pain control in cats undergoing elective ovariohysterectomy under continuous propofol infusion

This study evaluated the intraoperative and postoperative analgesic effects of an ultrasound-guided erector spinae plane (ESP) block with bupivacaine in cats undergoing elective ovariohysterectomy. Sixteen healthy client-owned female cats (with, 2.62 ± 0.46 kg; and, 23.06 ± 20.34 months) were randomly assigned to two groups (n = 8 each). All animals received dexmedetomidine (2.5 µg/kg, intramuscularly), followed by propofol administered to effect for induction and maintained as a continuous rate infusion beginning at 0.3 mg/kg/min adjusted as necessary. Ultrasound-guided bilateral ESP blocks were performed at the first lumbar vertebra using 0.25% bupivacaine (0.5 mL/kg per side) in the bupivacaine group, (GB) or 0.9% saline in the saline group (GS). Intraoperative Cardiopulmonary variables and nociceptive responses were recorded, and fentanyl (2.5 µg/kg, IV) was administered as analgesia rescue. Postoperative pain was assessed over 24 h using the UNESP–Botucatu Multidimensional Pain Scale (short-form) and the Feline Grimace Scale, with buprenorphine rescue (20 µg/kg, IM). Cats in GB required fewer intraoperative fentanyl rescue (27 vs. 35 administrations), corresponding to a 22.85% reduction in total fentanyl rescue compared with the GS, however, no statistical difference between groups (p = 0.5976). Intraoperative heart rate and systolic arterial pressure increased during periods of greater surgical stimulation in both groups, with no significant between-group differences. No significant differences were observed in postoperative requirement of analgesic rescue. (p = 0.9554). These findings indicate that the ESP block with bupivacaine provides effective intraoperative opioid-sparing analgesia but limited postoperative benefit, supporting its use as part of a multimodal analgesic approach in feline abdominal surgery.