Evaluation of a lidocaine with epinephrine infusion for reducing postoperative pain and complications in elective cat castrations

Abstract

This prospective, randomized, blinded clinical trial evaluated whether infusing lidocaine with epinephrine (LE) into spermatic cords during elective feline surgical castrations improved postoperative pain control and reduced acute postoperative complications. Five hundred one apparently healthy male cats presenting for elective surgical gonadectomy to a non-for-profit high-volume spay and neuter practice were entered into the study. Cats were a combination of feral, shelter-owned, and client-owned. Cats were anesthetized using a standardized, multimodal protocol that included buprenorphine, ketamine, dexmedetomidine. Cats were randomized to receive a LE infusion or no local treatment. A Simple Descriptive Scale (SDS) was used to assess acute postoperative pain at 1 and 3 h post-anesthesia recovery, and postoperative surgery-associated complications (swelling, bruising, and/or bleeding) were recorded prior to a same-day discharge from the hospital. The duration of anesthesia recovery and the quality of the recovery (pleasant, acceptable, or unpleasant) were also evaluated. No significant differences were observed between groups in pain scores, early complication rates, or subjective assessments of anesthesia recovery quality. Recovery durations were shorter in the LE group, although the clinical relevance of this difference (<1 min) is uncertain. Overall complication incidence and pain scores were low across groups. These findings suggest that, under conditions of experienced surgical technique and standardized multimodal anesthesia, LE infusion does not confer any additional, significant, measurable, clinically relevant benefits in the acute postoperative period. Future studies should incorporate validated feline pain scales and longer follow-up periods, including the post-discharge period, to better evaluate the potential effects on postoperative pain and complications.