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Comparison of NK-1 receptor antagonist (Maropitant) to morphine as a preanaesthetic agent for canine ovariohysterectomy




Marquez, Megan
Boscan, Pedro
Weir, Heather
Vogel, Pamela
Twedt, David C.

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Objective: To compare the NK-1 receptor antagonist maropitant to morphine during and after surgery in dogs undergoing ovariohysterectomy (OHE). Methods: 30 healthy female dogs were randomly divided to receive either a pre-anaesthetic dose of morphine (0.5 mg/kg SQ) or maropitant (1 mg/kg, SQ) prior to OHE. Anaesthesia was induced with propofol and maintained with isoflurane. Expired isoflurane concentration, heart rate (HR), systolic arterial pressure (SAP) and respiratory rate were measured. Post-operative pain scores and appetite were evaluated during the recovery period. Rescue analgesia (morphine 0.1 mg/kg IV) was administered as needed post-operatively based on blinded pain score assessments. Results: Although clinically comparable; during surgical stimulation, the maropitant group had lower HR (108±18 vs 115±24 bpm; p=0.04), lower SAP (114±23 vs 125±23 mmHg; p=0.003) and required slightly lower percent of isoflurane anaesthetic (1.35±0.2 vs 1.51±0.4 %; p=0.005), when compared to the morphine group. In the recovery period, the maropitant group had lower pain scores at extubation (1.7±0.7 vs 3.4±2.3; p=0.0001) and were more likely to eat within 3 hours after extubation (64.7 vs 15.3%). However, post-operative rescue analgesia requirements were similar between groups. All other measured parameters were similar between groups. The overall difference observed between groups was small and all monitored and measured parameters were within the expected range for anesthetized dogs. Clinical Significance: No major differences in cardiorespiratory parameters or anaesthetic requirements were observed between maropitant and morphine when used as a pre-anesthetic agent for OHE. Further studies are necessary to fully elucidate the benefits of maropitant as a pre-anaesthetic agent for canine OHE.


Zip file includes Prism files and ReadMe (i.e. synopsis). Prism software is needed to access the data files. All data is analyzed through the statistical software Prism. The software displays the data, statistical results and a preliminary graph.
Pedro Boscan is the corresponding author.
Department of Clinical Sciences

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