Comparative investigation of intraoperative analgesic effects of ketoprofen, meloxcam and buprenorphine used before orchiectomy in rabbits

Objective: This study aimed to comparatively investigate the intraoperative analgesic effects of ketoprofen, meloxicam and buprenorphine used before orchiectomy, a surgical procedure in rabbits. Material and Methods: The study material consisted of 24 male New Zealand White rabbits (Oryctolagus cuniculus), aged between 8 months and 3 years, weighing 2.5-5.5 kg. Rabbits are divided into four groups. The first group was the control group and no analgesic substance was used. Meloxicam (1 mg/kg) was administered to the animals in the second group, ketoprofen (3 mg/kg) to the animals in the third group, and buprenorphine (0.025 mg/kg) to the animals in the fourth group intramuscularly, 30 minutes before orchiectomy. Rabbits were anesthetized by the combined application of medetomidine at a dose of 0.25 mg/kg and ketamine at a dose of 35 mg/kg, 10 minutes after the injection of each analgesic agent. In the study, preoperative, intraoperative and postoperative heart rate (minute-1), respiratory frequency (minute-1), body temperature (°C) and peripheral oxygen saturation (SpO2 (%)) were measured, as well as pain scoring. During the study, approximately 0.5-1 ml of blood was also collected from the marginal ear vein of the rabbits into eppendorf tubes before any analgesic or anesthetic agent was given preoperatively, 10 minutes after ketamine-medetomidine anesthesia,following the end of orchiectomy and at 2, 4 and 6 hours postoperatively and serum cortisol levels were measured. Results: It was determined that the changes in heart frequencies did not differ between the groups in terms of each operation measurement time, however, the changes in each application group according to the operation times were not statistically significant. It was determined that the respiratory frequency did not change significantly between the groups in each time period, but the measurements taken in the preoperative period in the rabbits administered meloxicam were significantly lower (p=0.008) compared to the intraoperative period. In rabbits in the buprenorphine group, it was determined that intraoperative and postoperative measurements showed significant differences at (p=0.020) and (p=0.015), respectively, compared to preoperative measurements. It was determined that there was no difference between the groups in body temperature for each measurement time. In the measurements made at different times of the operation for each group, it was determined that there were statistically significant changes between the preoperative-postoperative and intraoperative-postoperative periods in the meloxicam applied group, and that there were significant changes between the preoperative-postoperative period in the buprenorphine group. In terms of SpO2 values, it was determined that ketoprofen and control group measurements were significantly lower in the intraoperative application groups compared to buprenorphine measurements. In the changes that occurred in each group's own time period, it was determined that the SpO2 levels of the control group animals were lower in the intraoperative and postoperative periods compared to the preoperative period, and in the ketoprofen applied group, the SpO2 level in the preoperative period was significantly higher than the postoperative period. However, it was determined that the SpO2 values of animals administered meloxicam in the postoperative period were significantly different from those of animals administered ketoprofen andbuprenorphine. It was determined that the time, group and group-time relationships of the changes in cortisol levels of animals that underwent orchiectomy surgery with the application of analgesic substances in the preoperative period were statistically significantly different. Based on the pain scores in the animal groups used in the study, it was determined that the median value of the pain score of the animals in the control group was 2, the median value of the pain score in the meloxicam and ketoprofen group was 1, and the median value of the pain score in the buprenorphine group was 0. Conclusions: It was concluded that orchiectomy operation in male rabbits may be a suitable study model for preemptive analgesia studies. An average statistical decrease of 0.5 °C was observed in preoperative and intraoperative body temperature values measured rectally in rabbits in the meloxicam and buprenorphine groups, and some anesthesia-related changes in heart rate and respiratory frequency were observed in rabbits during the study. Based on the serum cortisol level, which is an acute biomarker of pain and response to pain, it was concluded that buprenorphine has the strongest analgesic effect and ketoprofen has the weakest analgesic effect in orchiectomy operations in rabbits, at the doses and administration routes specified in the study. Key words: Pain, Analgesia, Intraoperative, Orchiectomy, Rabbit.