Analgesic and antihyperalgesic effects of dipyrone, meloxicam or a dipyrone–meloxicam combination in bitches undergoing ovariohysterectomy

•The analgesic effects of dipyrone, meloxicam or a combination were compared in ovariohysterectomised bitches.•Dipyrone produced superior analgesia than in untreated controls.•Meloxicam produced superior antihyperalgesia than in untreated controls.•The combined use of dipyrone and meloxicam produced both beneficial effects. The analgesic and antihyperalgesic effects of dipyrone, meloxicam or a dipyrone–meloxicam combination were compared in dogs undergoing elective ovariohysterectomy. In a double-blinded, prospective, randomised design, 40 bitches premedicated with intramuscular pethidine (4 mg/kg) and anaesthetised with isoflurane received one of four intravenous treatments (n = 10 per group) before ovariohysterectomy: control (physiological saline), meloxicam (0.2 mg/kg), dipyrone (25 mg/kg) or dipyrone–meloxicam (25 mg/kg and 0.2 mg/kg, respectively). Glasgow composite measure pain scale (GCMPS) and mechanical nociceptive thresholds (MNT) were assessed before anaesthesia and at 1, 2, 3, 4, 6, 8, 12 and 24 h postoperatively. Rescue analgesia (0.5 mg/kg morphine) was administered intramuscularly if the GCMPS was ≥3. The GCMPS and MNT did not differ among groups. The frequency of rescue analgesia was significantly (P