To establish if preoperative maropitant significantly reduced intraoperative isoflurane
requirements and reduced clinical signs associated with postoperative nausea and vomiting
(PONV) in dogs.
Randomized clinical trial.
Twenty-four healthy, client-owned dogs undergoing routine ovariohysterectomy.
Premedication involved acepromazine (0.03 mg kg−1) combined with methadone (0.3 mg kg−1) intramuscularly 45 minutes before anaesthetic induction with intravenous (IV) propofol,
dosed to effect. Meloxicam (0.2 mg kg−1) was administered intravenously. Dogs were randomly assigned to administration of
saline (group S; 0.1 mL kg−1, n=12) or maropitant (group M; 1 mg kg−1, n=12) subcutaneously at time of premedication. Methadone (0.1 mg kg−1 IV) 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
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.
Maropitant reduced overall intraoperative isoflurane requirements but did not affect
the incidence of PONV.
Maropitant provided no significant benefits to dogs undergoing ovariohysterectomy
with this anaesthetic and analgesic protocol, although clinically significant reductions
in isoflurane requirements were noted.