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Abstract

This was a randomized controlled clinical trial conducted to evaluate the effects of butorphanol, meloxicam and butorphanol-meloxicam combination on wound healing in dogs after ovariohysterectomy. Forty-eight healthy client-owned dogs scheduled for ovariohysterectomy were randomly assigned to four treatment groups of twelve animals each. The treatment groups were designated as B, M, BM and C. Dogs were sedated using acepromazine at 0.1mg/kg intramuscularly. Ten minutes later, induction was achieved by administering propofol at 5mg/kg intravenously. Anaesthesia was then maintained using isoflurane. Routine ovariohysterectomy was performed on each dog and test analgesics administered at the placement of the last skin suture. Dogs in group B received butorphanol at 0.2 mg/kg, group M received meloxicam at 0.2 mg/kg, group BM received butorphanol-meloxicam combination at half the dosage of each drug (0.1 mg/kg butorphanol and 0.1 mg/kg meloxicam), and those in group C, acting as the control, received saline at 0.5ml/10kg body weight. All the test analgesics and placebo were administered subcutaneously. Wound healing was assessed at 24, 48, 72 hours and 8 days, postoperatively using clinical appearance of wounds (swelling, erythema, dehiscence, discharge) and histopathology of wound biopsies (collagen, epithelialization, neovascularization, fibroblasts, macrophages and neutrophils). In this study, parametric variables were analyzed using ANOVA and student t-test while non-parametric variables were analyzed using Kruskal Wallis rank sum test and Mann Whitney test. Statistical significant was set at P<0.05. Dogs treated using meloxicam had significantly lower scores for clinical appearance of the wound compared to those under butorphanol (P=0.03) and those in the control group (P=0.02) but statistically similar scores to dogs under butorphanol-meloxicam combination (P=0.39). Dogs in the control group had the highest scores for wound swelling, erythema and dehiscence while those under meloxicam had the lowest scores. Histologically, wound biopsies from dogs under meloxicam and the butorphanol-meloxicam combination had better scores for collagen, epithelialization, neovascularization, fibroblasts, macrophages and neutrophils compared to dogs under butorphanol and those in the control group. Better response to wound healing was elaborated by more wound collagen, better epithelialization and neovascularization, more fibroblasts and gradual diminishing levels of neutrophil and macrophage numbers in dogs treated with analgesics in the postoperative period than in those in the control. This indicates an important interplay between pain, stress response and wound healing in dogs, postoperatively. Thus, to enhance patient comfort and improve on surgical outcome treatment of pain and minimizing perioperative stress is imperative.