The effect of maropitant on intraoperative isoflurane requirements and postoperative nausea and vomiting in dogs: a randomized clinical trial.

Abstract

OBJECTIVE: To establish if preoperative maropitant significantly reduced intraoperative isoflurane requirements and reduced clinical signs associated with postoperative nausea and vomiting (PONV) in dogs. STUDY DESIGN: Randomized clinical trial. ANIMALS: Twenty-four healthy, client-owned dogs undergoing routine ovariohysterectomy. METHODS: Premedication involved acepromazine (0.03 mg kg) combined with methadone (0.3 mg kg) intramuscularly 45 minutes before anaesthetic induction with intravenous (IV) propofol, dosed to effect. Meloxicam (0.2 mg kg) was administered intravenously. Dogs were randomly assigned to administration of saline (group S; 0.1 mL kg, n=12) or maropitant (group M; 1 mg kg, n=12) subcutaneously at time of premedication. Methadone (0.1 mg kgIV) was repeated 4 hours later. Anaesthesia was maintained with isoflurane in oxygen, dosed to effect by an observer unaware of group allocation. The dogs were assessed hourly, starting 1 hour postoperatively, using the short form of the Glasgow Composite Pain Score (GCPS), and for ptyalism and signs attributable to PONV [score from 0 (none) to 3 (severe)] by blinded observers. Owners completed a questionnaire at the postoperative recheck. RESULTS: Overall mean±standard deviation end-tidal isoflurane percentage was lower in group M (1.19±0.26%) than group S (1.44±0.23%) (p=0.022), but was not significantly different between groups at specific noxious events (skin incision, ovarian pedicle clamp application, cervical clamp application, wound closure). Cardiorespiratory variables and postoperative GCPS were not significantly different between groups. Overall, 50% of dogs displayed signs attributable to PONV, with no difference in PONV scores between groups (p=0.198). No difference in anaesthetic recovery was noted by owners between groups. CONCLUSIONS: Maropitant reduced overall intraoperative isoflurane requirements but did not affect the incidence of PONV. CLINICAL RELEVANCE: Maropitant provided no significant benefits to dogs undergoing ovariohysterectomy with this anaesthetic and analgesic protocol, although clinically significant reductions in isoflurane requirements were noted.