Preoperative protocol for right flank laparotomy affects postoperative serum cortisol concentrations in dairy cows.

Abstract

To evaluate analgesic efficacy of 3 different preoperative protocols in cows undergoing right flank laparotomy for displaced abomasum. 40 cows diagnosed with displaced abomasum. The cows were assigned by block randomization to 1 of 3 preoperative protocols: inverted L-block using 50 mL of 2% lidocaine (ILB; n = 13), ILB plus preoperative flunixin meglumine (2 mg/kg, IV; ILB-F; 13), and dorsolumbar epidural anesthesia using 2% xylazine (0.8 mL) and 2% lidocaine (4 mL; EPI; 14). Venous blood samples were collected for CBC, serum biochemistry, and cortisol preoperatively and at 0 (immediately after), 3, 17, and 48 hours postoperatively. The mean (95% CI) of the serum cortisol in ILB, ILB-F, and EPI were 108.7 (66.7 to 150.7), 150.7 (116.4 to 185.0), and 139.8 (93.4 to 186.3), respectively. The serum cortisol concentrations decreased over time in all groups (ILB, P = .001; ILB-F and EPI, P < .001). In the ILB group, the cortisol concentration at 17 and 48 hours postoperatively decreased (P = .026 and P = .009, respectively), compared with that preoperatively. In the ILB-F and EPI groups, the preoperative cortisol concentration was the highest and then decreased at 0, 3, 17, and 48 hours postoperatively (ILB-F, 0 hours [P = .001] and 3, 17, and 48 hours [P < .001]; EPI, all [P < .001]). ILB-F and EPI improved intraoperative and immediate postoperative indicators of pain-related stress when compared to standard ILB. EPI requires less anesthetic, which may be beneficial when in short supply.