# 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

## TL;DR

An erector spinae plane block with bupivacaine reduced opioid use during surgery in cats but did not significantly improve postoperative pain control.

## Contribution

The study is the first to evaluate the intraoperative and postoperative analgesic effects of ESP blocks in cats undergoing abdominal surgery.

## Key findings

- ESP block with bupivacaine reduced intraoperative fentanyl use by 22.85% but not significantly.
- No significant differences in postoperative analgesic requirements between groups.
- ESP block may support multimodal analgesia during surgery but offers limited postoperative benefit.

## Abstract

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.