ASSESSMENT OF XYLAZINE HYDROCHLORIDE EPIDURAL ANALGESIA FOR OPEN CASTRATION OF RAMS

Epidural xylazine injected at the sacrococcygeal site 40 to 150 min pr ior to surgery (at a dose of 0.05 to 0.10 mg/kg) provided good analges ia during scrotal skin incision in all 20 experimental rams but in onl y 10 rams (50%) at incision and separation of tunica vaginalis, and 6 rams (30%) during ligation of the spermatic cord. There was a signific ant correlation between the decrease in heart rate and the dosage of e pidural xylazine. Heart rate increased significantly during incision o f the tunics and spermatic cord ligation but was not significantly cor related to the clinical assessment of analgesia. There was no signific ant correlation between the presence of surgical analgesia and the dos age of epidural xylazine. Pelvic limb ataxia was still evident in 12 r ams (60%) at 8 h after epidural xylazine injection. Epidural xylazine provided good somatic analgesia during open castration of 20 rams but visceral analgesia was unpredictable. Factors in addition to the dosag e of sacrococcygeal epidural xylazine affects the degree of surgical a nalgesia obtained for open castration of rams.