Effect of preoperative ondansetron on postoperative nausea in healthy dogs undergoing laparoscopic gastropexy and castration.

Objective: To investigate if preoperative ondansetron reduces postoperative nausea associated with laparoscopic gastropexy and castration in dogs.

Study Design: Prospective clinical study.

Animals: Twenty client-owned, healthy male dogs.

Methods: Dogs were premedicated with dexmedetomidine (2-5 mcg kg) and methadone (0.2-0.5 mg kg) intramuscularly. General anesthesia was induced with propofol and maintained with an inhalant anesthetic agent. Dogs were randomized into group S (saline 0.1 mL kg, intravenously) or group O (ondansetron 0.2 mg kg, intravenously). Plasma and serum were collected before premedication and 3 hours postextubation to measure arginine vasopressin (AVP) and cortisol concentrations. Nausea scoring occurred before and 10 minutes after premedication, immediately after extubation, and at 1, 2 and 3 hours postextubation. Data were analyzed by mixed and split-plot anova with Bonferroni adjustment for the number of group comparisons. Significance was set at p < 0.05.

Results: Nausea scores increased over time at 1 (p = 0.01) and 2 (p < 0.001) hours postextubation in both groups compared with before premedication. Median nausea score (0-100 mm) for groups S and O before premedication were 2.5 and 0.5 mm, respectively. At 1 and 2 hours postextubation, group S scored 7.5 and 4.0 mm and group O scored 6.0 and 5.0 mm, respectively. No significant differences in nausea scores within or between groups were observed before premedication and 3 hours postextubation. Cortisol concentrations increased significantly 3 hours postextubation in both groups (p < 0.001) compared with before premedication, with no differences between groups. AVP concentrations showed no significant differences within or between groups.

Conclusions And Clinical Relevance: Preoperative intravenous administration of ondansetron (0.2 mg kg) did not impact postoperative nausea after laparoscopic gastropexy and castration. Investigation of higher doses of ondansetron on the incidence of postoperative nausea and vomiting in dogs after surgery is warranted.