Effect of intraperitoneal or incisional bupivacaine on pain and the analgesic requirement after ovariohysterectomy in dogs

To compare the effect of intraperitoneal (IP) or incisional (INC) bupivacaine on pain and the analgesic requirement after ovariohysterectomy in dogs. Prospective, randomized clinical study. Thirty female dogs undergoing ovariohysterectomy (OHE). Dogs admitted for elective OHE were anesthetized with acepromazine, butorphanol, thiopental and halothane. Animals were randomly assigned to one of three groups (n = 10 per group). The treatments consisted of preincisional infiltration with saline solution (NaCl 0.9%) or bupivacaine with epinephrine and/or IP administration of the same solutions, as follows: INC and IP 0.9% NaCl (control group); INC 0.9% NaCl and IP bupivacaine (5 mg kg−1, IP group); INC bupivacaine (1 mg kg−1) and IP 0.9% NaCl (INC group). Postoperative pain was evaluated by a blinded observer for 24 hours after extubation by means of a visual analog scale (VAS) and a numeric rating scale (NRS). Rescue analgesia (morphine, 0.5 mg kg−1, IM) was administered if the VAS was >5/10 or the NRS >10/29. At 1 hour after anesthesia, VAS pain scores were [medians (interquartile range)]: 6.4 (3.1–7.9), 0.3 (0.0–2.6) and 0.0 (0.0–7.0) in control, IP and INC groups, respectively. VAS pain scores were lower in the IP compared to the control group. Over the first 24 hours, rescue analgesia was administered to 7/10, 5/10 and 3/10 dogs of the control, INC and IP groups, respectively. Total number of dogs given rescue analgesia over the first 24 hours did not differ significantly among groups. Intraperitoneal bupivacaine resulted in lower pain scores during the first hour of the postoperative period and there was a trend towards a decreased need for rescue analgesia after OHE in dogs.