Efficacy and safety of a fixed-dose oral tramadol-dipyrone combination for postoperative analgesia in dogs undergoing ovariohysterectomy and unilateral mastectomy: a randomized clinical trial.

INTRODUCTION: To evaluate the analgesic efficacy and safety of an oral tramadol-dipyrone combination (Sindolor®) compared with tramadol or dipyrone alone in dogs undergoing ovariohysterectomy and unilateral mastectomy. METHODS: Thirty client-owned female dogs undergoing elective ovariohysterectomy and unilateral mastectomy were randomly assigned to three treatment groups (n = 10/group): tramadol-dipyrone combination (GTD), tramadol alone (GT), or dipyrone alone (GD). At the end of surgery, all dogs received meloxicam and the first intravenous dose of the assigned treatment. Oral treatment began approximately 8 h later and continued every 8 h for 5 days. Postoperative pain was assessed using the Glasgow Composite Measure Pain Scale-Short Form (GCMPS-SF), a dynamic interactive visual analog scale (DIVAS), and serum cortisol concentrations. Rescue analgesia with intravenous morphine was administered when predefined thresholds were reached. RESULTS: Pain scores decreased significantly over time in all groups (p < 0.01). Despite concurrent meloxicam administration, dogs receiving dipyrone alone showed higher GCMPS-SF scores than those treated with the tramadol-dipyrone combination at D + 1 afternoon (p < 0.01). Pain incidence analysis demonstrated a higher proportion of pain-free dogs in the combination group during the early postoperative period. Overall rescue analgesia frequency did not differ significantly among groups; however, after initiation of oral treatment, rescue analgesia was required in two dogs from both GT and GD, whereas no dog in GTD required additional analgesia. Cortisol concentrations remained within the reference range in GTD, whereas transient increases above the reference interval were observed in GT and GD. No clinically relevant adverse effects were observed. CONCLUSIONS AND CLINICAL RELEVANCE: The tramadol-dipyrone combination improved early postoperative pain control in dogs undergoing ovariohysterectomy and unilateral mastectomy while maintaining favorable tolerability. These findings support its clinical use as part of a multimodal postoperative analgesic protocol, particularly during the early postoperative period.