The analgesic effects of butorphanol and meloxicam after elective ovariohysterectomy in dogs

Abstract

This study was designed to compare the analgesic effects of meloxicam and butorphanol following elective ovariohysterectomy. Group A (15 dogs) was pre-medicated with 0.05 mg kg−1 IM of acepromazine plus 0.2 mg kg−1 SC of meloxicam. Group B (15 dogs) was pre-medicated with 0.05 mg kg−1 IM of acepromazine plus 0.2 mg kg−1 IM of butorphanol. Both groups were induced to anesthesia with approximately 10 mg kg−1 of thiopental and maintained on halothane in oxygen. All of the ovariohysterectomies were performed by a faculty surgeon or senior surgical resident. Following surgery, the dog was maintained in the recovery area for observation. All pain measurements were performed by one experienced individual. The observer was blinded to treatment. Pain scores (0–10) and VAS scores were performed at 2, 3, 4, 6, 12, and 24 hours post-premedication. An analgesiometer was used to determine the pressure required to produce an active avoidance response to pressure applied at the incision line. The analgesiometer was applied after the determination of pain and VAS scores. The association between treatment status (meloxicam or control), sample time and pain, VAS or analgesiometer scores were analyzed using a generalized estimating equation (GEE) method to account for over dispersion within the data resulting from the repeated measures design. Mucosal bleeding times were performed prior to pre-medication, and at 6 and 24 hours post-premedication. The 6 and 24 hour readings were compared to baseline with a paired t-test. Any animal with a pain score >3 received rescue analgesia (butorphanol 0.2 mg kg−1 IM). Data from these animals, up to rescue analgesia, was included in the analysis. A significance level of p < 0.05 was considered significant. Surgery time was 27 ± 16 minutes in the meloxicam group and 26 ± 8 minutes in the butorphanol group. The animals in group A (meloxicam) demonstrated significantly lower pain and VAS scores, compared to group B. There was no difference in analgesiometry scores and mucosal bleeding times did not change significantly with either treatment. Two animals required rescue analgesia. Both of these animals were in group B. Results of this study suggest that 0.2 mg kg−1 of meloxicam will provide superior analgesia to 0.2 mg kg−1 of butorphanol in dogs following ovariohysterectomy.