Intraperitoneal and incisional ropivacaine did not improve postoperative analgesia after multimodal anaesthesia compared with saline in dogs undergoing ovariohysterectomy.

Abstract

Introduction: Intraperitoneal administration of local anaesthetics may reduce postoperative pain after ovariohysterectomy in dogs. The aim of this prospective, randomised, blinded, placebo-controlled clinical trial was to compare postoperative analgesia and opioid requirements after intraperitoneal and incisional administration of ropivacaine versus 0,9 % NaCl (saline). Forty-three client-owned dogs were enrolled in the study and anaesthetised using a standardized protocol that included premedication with acepromazine (0,03-0,05 mg/kg) and dexmedetomidine (0,01 mg/kg) intramuscularly. Anaesthesia was induced with propofol titrated to effect and ketamine (1 mg/kg) intravenously and maintained with isoflurane in oxygen. The analgesic regimen included carprofen (4 mg/kg) subcutaneously and morphine (0,2 mg/kg) intravenously. Depending on group assignment, each dog received either an intraperitoneal and incisional splash with ropivacaine (2 mg/kg and 1 mg/kg, respectively) (group R), or an equal volume of saline (group S). Buprenorphine (0,02 mg/kg) was administered intramuscularly once the uterus was removed. Sedation and pain were assessed 0,5, 1, 2, 4, 6 and 8 hours after extubation using a sedation scale, the short form of the Glasgow Composite Pain Scale (CMPS-SF) and a dynamic interactive visual analogue scale (DIVAS). Postoperatively, buprenorphine (0,01 mg/kg) was administered intravenously if dogs scored 6/24 on CMPS-SF. The ordinal mixed model showed no difference in pain scores between groups. Fisher's exact test showed no significant difference in postoperative buprenorphine requirements between group S (3/22 dogs) and group R (1/21 dogs) at the doses used. In addition, lower sedation scores were associated with higher DIVAS scores. In this multimodal analgesic protocol, ropivacaine could not improve analgesia compared to saline.