A Comparison of Epidural Saline, Morphine, and Bupivacaine for Pain Relief After Abdominal Surgery in Goats

The purpose of this study was to determine the analgesic efficacy of bupivacaine, morphine, or saline (control) when injected epidurally into the lumbosacral epidural space in goats after abdominal surgery. Goats received either bupivacaine (0.5%; 1.5 mg/kg in 0.9% sodium chloride solution), 0.9% sodium chloride solution (0.2 mL/kg), or preservative-free morphine (0.1 mg/kg). Total volume injected into the epidural space was 0.2 mL/kg for all groups. The variables evaluated were times to extubation, sternal recumbency, standing, and eating; heart and respiratory rates; and pain score. Only two of the goats in the bupivacaine group were able to stand on their hindlimbs before 6 hours. Time to eating was shorter for the saline group when compared with the bupivacaine group. Heart rate over all time in the saline group (137 +/- 4 beats/min, mean +/- SEM) was higher than the morphine (125 +/- 3 beats/min) and bupivacaine groups (121 +/- 3 beats/min). Respiratory rate over all time was increased in the saline group (26 +/- 1 breaths/min) compared with the bupivacaine (24 +/- 1 breaths/min) or morphine (24 +/- 1 breaths/min) groups. At 50 minutes, the pain score for the saline group was higher than the morphine group. Pain score over all time in the saline group (1.5 +/- 0.10) was higher than the morphine (1.2 +/- 0.07) and bupivacaine (1.2 +/- 0.04) groups. One goat in the saline group required two intravenous injections of flunixin meglumine for pain.