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ORIGINAL RESEARCH article

Front. Vet. Sci.

Sec. Anesthesiology and Animal Pain Management

Volume 12 - 2025 | doi: 10.3389/fvets.2025.1648665

Effect of a novel sternal recumbency approach for quadratus lumborum block on isoflurane requirements in cats undergoing ovariohysterectomy

Provisionally accepted
  • 1Seibozaka Animal Hospital, Tokyo, Japan
  • 2Vet Surg Tokyo, Tokyo, Japan

The final, formatted version of the article will be published soon.

This prospective, randomized clinical study with a sequential design aimed to evaluate whether a novel quadratus lumborum block (QLB) technique applied in sternal recumbency could reduce isoflurane requirements and enhance procedural safety in cats undergoing ovariohysterectomy. Methods: Thirty-five American Society of Anesthesiologists physical status (ASA-PS) I female cats, either client-owned or sheltered, undergoing ovariohysterectomy. Cats were randomly assigned to different groups to undergo either conventional QLB technique in lateral recumbency (CQLB group, n = 17) or novel QLB technique in sternal recumbency (NQLB group, n = 18). Ultrasound-guided injections were performed bilaterally, targeting the fascial plane between the quadratus lumborum and psoas minor muscles, with 0.4 mL kg -¹ bupivacaine administered per side. Cats were premedicated with dexmedetomidine, anesthetized with propofol and isoflurane. The end-tidal isoflurane concentration (ETiso) was adjusted based on heart rate (HR), respiratory rate, and mean arterial pressure (MAP). Outcomes included total mean ETiso, phase-specific ETiso, total mean HR and MAP, rate of needle proximity to abdominal organs, rates of bradycardia, hypotension, and the need for postoperative analgesics, assessed using both the Short-form UNESP-Botucatu Multidimensional Composite Pain Scale and the Feline Grimace Scale. Results: Cats in the NQLB group demonstrated slightly lower total mean ETiso (p = 0.046) and significantly reduced ETiso during right ovariectomy (p = 0.022) and hysterectomy (p = 0.007) compared with cats in the CQLB group. Total mean HR and MAP did not differ between groups. Needle proximity to abdominal organs was observed in all CQLB cats but not in any NQLB cats. No bradycardia or hypotension was observed. There was no significant difference in the requirement for postoperative rescue analgesic between the groups. Discussion: The novel QLB technique demonstrated a superior isofluranesparing effect and safety compared with that of conventional QLB in cats. This approach may benefit cats undergoing ovariohysterectomy.

Keywords: feline, QLB, isoflurane-sparing effect, regional anesthesia, Ultrasound-guided nerve block

Received: 17 Jun 2025; Accepted: 22 Aug 2025.

Copyright: © 2025 Takusagawa, Takusagawa and Kimura. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Fumihiko Takusagawa, Seibozaka Animal Hospital, Tokyo, Japan

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