Efficacy of oral transmucosal administrations of phenylbutazone for postoperative analgesia in dogs undergoing ovariohysterectomy

The aim of the present study was to evaluate the efficacy and analgesic duration of a single dose of Phenylbutazone (PBZ) administered by the oral transmucosal (OTM) or via the intravenous (IV) route immediately before induction of anesthesia in dogs undergoing elective ovohysterectomy (OVH). Twenty-seven sexually intact female dogs referred for OVH procedure from a local shelter at regular intervals over 3 months, were included in the study. The dogs were administered PBZ and the placebo on the basis of their respective treatment group (20 mg/kg, IV; 20 mg/kg via OTM administration; 1.75 ml/kg IV 0.9% NaCl) before administration of xylazine. Throughout the study, vital signs were measured at baseline (T0, before administration of PBZ) and then at 5 (T1), 10 (T2), 15 (T3), 20 (T4), 25 (T5), and 30 (T6) minutes intraoperatively. Postoperative pain was assessed at 0.5, 1, 2, 3, 8, and 24 hours after operation. Groups OTM and IV had significantly lower Composite Measure Pain Scale (CMPS-SF) scores (p˂0.05) than the control group at the 0.5, 1, 2, 3, and 8 hours postoperatively. The analgesic (carprofen) was used with all dogs. In conclusion, a single dose of PBZ administered via the OTM route before surgery provided some analgesia but was not enough on its own for the postoperative period. Additionally, PBZ administred via the OTM route did not provide a dissimilar analgesia than the IV route.