Use of subcutaneous maropitant at two dosages for pain management in domestic rabbits ( Oryctolagus cuniculus ) undergoing elective ovariohysterectomy or orchiectomy

Objective: To describe the effect of two doses of maropitant on pain scores, food intake, and fecal output in domestic rabbits (Oryctolagus cuniculus) undergoing elective ovariohysterectomy or orchiectomy. Animals: 26 (11 female, 15 male) rabbits from three institutions. Procedures: Rabbits were randomly assigned to one of three treatment groups: low-dose maropitant (LDM; 2 mg/ kg SC once; n=8), moderate-dose maropitant (MDM; 4 mg/kg SC once; n=10), and control (saline equivalent to 4 mg/kg maropitant SC once; n=8), administered prior to surgery. Following surgery, all rabbits were provided buprenorphine (0.06 mg/kg q 8 hours) and meloxicam (1 mg/kg q 24 hours) intramuscularly. Rabbits were monitored using video surveillance postoperatively until 24 hours after surgery or discharge from the hospital, whichever came first. Pain scores were assessed by three blinded observers, and results were grouped into early (0-4 hours), mid (5-8 hours), and late (12-24 hours) time frames. Food intake and fecal output were compared between groups. Statistical analysis was performed using Chi square, Fisher's exact tests, and a mixed model approach. Results: There were no adverse effects with maropitant administration. Rabbits that received MDM had significantly lower pain scores in the mid-time frame and behavior scores in the late-time frame compared to controls. Male rabbits consumed more food than females and rabbits hospitalized longer than 12 hours consumed more food than those that were discharged prior. No significant differences were detected in facial grimace scale scores, food intake, or fecal production among treatment groups. Conclusions and clinical relevance: Moderate dose maropitant decreased pain related behaviors in the mid-time frame and behavior scores in the late-time frame after surgery. Further studies are necessary to better characterize the potential use of maropitant in postoperative analgesia.