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

Abstract

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 ± 28 months and weighing 11.3 ± 4.5 kg.

Methods: Dogs were premedicated with acepromazine (0.05 mg kg^-1) and morphine (0.5 mg kg^-1) intramuscularly (IM). Anaesthesia was induced with alfaxalone and maintained with isoflurane in oxygen. Carprofen (4 mg kg^-1) was injected subcutaneously after intubation. Dogs were randomly assigned to receive either bupivacaine (group B; 3 mg kg^-1) or ropivacaine (group R; 3 mg kg^-1) 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^-1) was administered in case of ≥ 5/20 or ≥ 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.

Keywords: bupivacaine; canine; intraperitoneal analgesia; local anaesthesia; ropivacaine.