Efficacy of oral transmucosal and intravenous administration of buprenorphine before surgery for postoperative analgesia in dogs undergoing ovariohysterectomy

OBJECTIVE: To compare the efficacy of preoperative administration of buprenorphine (via oral transmucosal [OTM] and IV routes) for postoperative analgesia in dogs undergoing ovariohysterectomy. DESIGN: Prospective, randomized, blinded study. ANIMALS: 18 dogs undergoing routine ovariohysterectomy. PROCEDURES: Dogs were allocated to 3 groups (6 dogs/group) and were assigned to receive buprenorphine (20 μg/kg [9.09 μg/lb], IV; a low dose [20 μg/kg] via OTM administration [LOTM]; or a high dose [120 μg/kg [54.54 μg/lb] via OTM administration [HOTM]) immediately before anesthetic induction with propofol and maintenance with isoflurane for ovariohysterectomy. Postoperative pain was assessed by use of a dynamic interactive pain scale. Dogs were provided rescue analgesia when postoperative pain exceeded a predetermined threshold. Blood samples were collected, and liquid chromatography-electrospray ionization-tandem mass spectrometry was used to determine plasma concentrations of buprenorphine and its metabolites. Data were analyzed with an ANOVA. RESULTS: Body weight, surgical duration, propofol dose, isoflurane concentration, and cardiorespiratory variables did not differ significantly among treatment groups. Number of dogs requiring rescue analgesia did not differ significantly for the HOTM (1/6), IV (3/6), and LOTM (5/6) treatments. Similarly, mean ± SEM duration of analgesia did not differ significantly for the HOTM (20.3 ± 3.7 hours), IV (16.0 ± 3.8 hours), and LOTM (7.3 ± 3.3 hours) treatments. Plasma buprenorphine concentration was ≤ 0.60 ng/mL in 7 of 9 dogs requiring rescue analgesia. CONCLUSIONS AND CLINICAL RELEVANCE: Buprenorphine (HOTM) given immediately before anesthetic induction can be an alternative for postoperative pain management in dogs undergoing ovariohysterectomy.