DVM Candidate Colorado State University Fort Collins
Abdominal surgery is commonly performed in horses. Options for postoperative pain management are associated with potentially life-threatening side effects. Liposomal local anesthetic solutions may provide extended-duration analgesia but have not been assessed for safety or efficacy following intra-abdominal administration in any species. The objective was to evaluate two doses of 1.33% liposomal bupivacaine (LB) versus 0.75% bupivacaine HCL (BHCl) for analgesia following laparoscopic ovariectomy in mares. Fifteen healthy Quarter Horse mares with normal bilateral ovarian palpation/appearance were enrolled. Bilateral standing paralumbar fossa ovariectomies were performed (one laparoscopic, two instrument portals per side). Treatment with either 20 or 40mL LB (LB20, LB40) (n=6/group) volume expanded with saline to 80mL or 80mL BHCl (n=3) was infused around incision sites and mesovarium bilaterally prior to removal. Horses were monitored 72h by physical examination and pain scoring (Bussieres Composite Pain Scale, Horse Grimace Scale), and peritoneal fluid analysis at 72h. Analgesia achieved with all protocols allowed completion of procedures. Pressure algometry scores were lower (worse) in BHCl treated horses compared to both LB groups at 24,32,48h and BHClvsLB40 at 56h. Horse grimace scale pain scores were higher in BHClvsLB20 and LB40 at 8,24h. Composite pain scores were higher in the BHClvsLB40 groups at 24h. Peritoneal fluid total protein levels were lower in LB40vsLB20 and BHCl at 72h. No complications resulting from LB were appreciated. Study limitations included small patient sample size, lack of follow-up past 72h or histopathology. Analgesia was extended and pain scores improved with LB vs BHCl in a dose dependent fashion.
