Intraperitoneal bupivacaine with or without incisional bupivacaine for postoperative analgesia in dogs undergoing ovariohysterectomy

Intraperitoneal (IP) bupivacaine provides postoperative analgesia in dogs undergoing ovariohysterectomy (OHE) alone or in combination with incisional (INC) bupivacaine. This study investigated whether the combination of INC and IP bupivacaine is superior to IP bupivacaine alone. Prospective, randomized, blinded clinical study. Thirty-nine privately owned dogs undergoing OHE, aged 25 ± 23 months and weighing 11.8 ± 5.7 kg. Dogs were premedicated with acepromazine (0.05 mg kg−1) and morphine (0.5 mg kg−1) intramuscularly (IM); anaesthesia was induced with propofol and maintained with isoflurane in oxygen. Carprofen (4 mg kg−1) was administered subcutaneously (SC) after intubation. Bupivacaine (3 mg kg−1) IP was administered before complete closure of the linea alba to all dogs. Dogs were randomly assigned into two groups: group B received bupivacaine (n = 20; 1 mg kg−1) and group S received saline (n = 19; 0.2 mL kg−1) INC as a subcutaneous ‘splash’ before skin closure. Postoperative analgesia was assessed with a dynamic interactive visual analogue scale, the short form of the Glasgow Composite Pain Scale, and mechanical nociceptive threshold (MNT) measurement at 0.5, 1, 2, 4, 6, 8, 12 and 20 hours after surgery by one blinded observer. Parametric data were tested using t-test; nonparametric data were analysed using the two-sample Wilcoxon test (p < 0.05). There was no significant difference between groups with regard to age, weight, surgical and anaesthetic duration, incision length, sedation and pain scores. MNT values decreased in both groups at all time points as compared with the baseline. No dog required rescue analgesia. No postoperative complications were observed. Bupivacaine IP and carprofen SC after morphine IM did provide satisfactory postoperative analgesia in dogs undergoing OHE with the anaesthetic protocol used. There appears to be no clinical advantage to adding bupivacaine INC. Neither protocol could prevent the development of primary hyperalgesia.