Analgesic efficacy of pregabalin in dogs undergoing mastectomy with ovariohysterectomy

The aim of this study was to evaluate the analgesic efficacy of pregabalin in dogs diagnosed with mammary carcinoma undergoing mastectomy with ovariohysterectomy. In a randomized, blinded, clinical, placebo-controlled study, 24 dogs were assigned to receive either an oral pregabalin suspension (4 mg/kg/0.1 mL/kg, Pregabalin group, n = 12) or a placebo solution (0.1 mL/kg, Placebo group, n = 12), administered 60 minutes before and every 8 hours after surgery. The dogs were premedicated with intramuscular (IM) morphine (0.3 mg/kg). Anesthesia was induced with intravenous (IV) propofol at a sufficient dose to allow intubation and was maintained with isoflurane. Intraoperatively, a constant rate infusion of morphine (0.1 mg/kg/h) was maintained until the end of surgery. Meloxicam (0.2 mg/kg, IV) was administered immediately after intubation. Intraoperatively, fentanyl (2.5 µg/kg, IV) was administered to control cardiovascular responses to surgical stimulation. Pain was assessed using the short-form Glasgow Composite Pain Scale 24 hours prior to surgery (baseline) and at 0.5, 1, 2, 4, 6, 8, 12, and 24 hours after extubation. Sedation scores were evaluated at the same time points using a descriptive numerical scale. Morphine (0.5 mg/kg, IM) was administered as rescue analgesia. Data were analyzed using t-tests, Fisher's exact test, Kaplan-Meier curve, Mann-Whitney test, and Friedman test. Differences were considered significant when P < 0.05. Pain scores, sedation scores, and analgesic requirements did not differ significantly between groups. Intraoperative fentanyl and postoperative rescue analgesia were required in 100% and 75% of the dogs, respectively, in both treatment groups. In conclusion, as part of a multimodal analgesic protocol, oral pregabalin at 4 mg/kg every 8 hours did not provide additional postoperative analgesic benefits over placebo in dogs undergoing mastectomy with ovariohysterectomy.