Anaesthetic sparing effect of lidocaine during ovariohysterectomy in bitches premedicated with remifentanil

This prospective, randomized, blinded study evaluated the anaesthetic-sparing effect of topical lidocaine applied to the mesovarium during ovariohysterectomy in bitches premedicated with remifentanil. Twenty healthy female dogs undergoing elective ovariohysterectomy were randomly assigned to a lidocaine group (L, n = 10) or control group (C, n = 10). Anaesthesia was induced with propofol and maintained with sevoflurane. In the L group, 2% lidocaine (2 mg/kg) was applied as a splash block to the mesovarium, while saline was applied in the controls. End-tidal sevoflurane concentration (Fe´Sevo), heart rate (HR), respiratory rate (f_R), invasive systolic and diastolic arterial blood pressure (IBPs, IBPd) and mean arterial pressure (MAP) were recorded at predefined time points. Fe´Sevo was down titrated in response to haemodynamic changes. Significant differences in Fe´Sevo were observed between groups, with lower concentrations required in the L group. Significant interactions between treatment and time were detected for HR, IBPd, MAP and f_R. The findings indicate that topical lidocaine reduces inhalation anaesthetic requirements and attenuates nociceptive responses during ovarian manipulation. The intraoperative use of lidocaine as part of multimodal analgesia may therefore provide clinical benefits in dogs undergoing ovariohysterectomy.