Lidocaine injection in dog ovaries to reduce spay surgery pain

Abstract

OBJECTIVE: To evaluate effects of lidocaine 2% administration into the ovarian pedicle on intraoperative nociception and early postoperative pain in dogs undergoing ovariohysterectomy. STUDY DESIGN: Prospective, randomized, blinded clinical study. ANIMALS: A total of 20 healthy adult female dogs of different breeds. METHODS: Dogs were premedicated with acepromazine (0.02 mg kg) and morphine (0.5 mg kg) intramuscularly, anesthesia induced with propofol and maintained with isoflurane. Dogs were randomly assigned to be administered 2 mL of saline (group S) or lidocaine 2% (group L) into the mesovarium (1 mL each side). Heart rate (HR) and noninvasive systemic arterial pressure were recorded before surgery (T0), before (T1) and during ligation of the right ovarian pedicle (T2), before (T3) and during ligation of the left ovarian pedicle (T4). Rescue treatment (propofol) was administered if HR or systolic arterial pressure (SAP) increased by 20% compared with the previous time point. Pain, assessed with the Glasgow Composite Measure Pain Scale-Short Form (CMPS-SF) was recorded before premedication (baseline) and after extubation. Administration of postoperative rescue analgesia was recorded. RESULTS: In group S, HR was higher at T2 than T1 (112 ± 18 versus 89 ± 21 beats minute, p = 0.001) There were no significant differences between treatments at any time. SAP was higher at T2 than T1 in group S (110 ± 12 versus 100 ± 10 mmHg, p = 0.031). SAP was higher in group S than group L at T3 (113 ± 12 and 91 ± 10 mmHg, respectively, p = 0.001). No dogs required propofol intraoperatively. All dogs required postoperative rescue analgesia. Compared with baseline, CMPS-SF increased 60 minutes after extubation (group S; p = 0.019, group L; p = 0.043). CONCLUSIONS AND CLINICAL RELEVANCE: Administration of lidocaine 2% into the mesovarium did not reduce intraoperative nociception and did not improve postoperative analgesia.