Comparison of intraperitoneal ropivacaine and bupivacaine for postoperative analgesia in dogs undergoing ovariohysterectomy

Objective: To compare postoperative analgesia following either intraperitoneal (IP) ropivacaine or bupivacaine in dogs undergoing ovariohysterectomy (OVH) in the scope of multimodal analgesia. Study design: Prospective, randomized, blinded clinical study. Animals: A total of 45 privately owned dogs undergoing OVH, aged 37 \ub1 28 months and weighing 11.3 \ub1 4.5 kg. Methods: Dogs were premedicated with acepromazine (0.05 mg kg 121) and morphine (0.5 mg kg 121) intramuscularly (IM). Anaesthesia was induced with alfaxalone and maintained with isoflurane in oxygen. Carprofen (4 mg kg 121) was injected subcutaneously after intubation. Dogs were randomly assigned to receive either bupivacaine (group B; 3 mg kg 121) or ropivacaine (group R; 3 mg kg 121) IP prior to complete closure of the linea alba. At 0.5, 1, 2, 4, 6 and 8 hours after extubation, sedation and postoperative pain were assessed, using the short form of the Glasgow Composite Pain scale (GCPS-SF), a dynamic interactive visual analogue scale (DIVAS), and mechanical nociceptive threshold (MNT) measurement. Rescue morphine (0.2 mg kg 121) was administered in case of 65 5/20 or 65 6/24 in the GCPS-SF and/or >40 mm in the DIVAS. Parametric data were compared using the t test; nonparametric data were analysed with the two-sample Wilcoxon test (p < 0.05). Results: The GCPS-SF score was significantly higher in group R at 8 hours. There was no other significant difference regarding sedation or analgesia between the groups. Rescue analgesia was administered to 15 dogs (R: 9/22; B: 6/22), with no significant difference between the groups. MNT values decreased in both groups at all time points when compared to baseline. No adverse effects were observed. Conclusions and clinical relevance: Ropivacaine or bupivacaine IP in combination with morphine IM and carprofen SC provided comparable postoperative analgesia in dogs after OVH for 6 hours. However, the anaesthetic protocol used did not prevent the administration of rescue analgesia in 41% of animals