Comparison of intraperitoneal ropivacaine and ropivacaine-dexmedetomidine for postoperative analgesia in cats undergoing ovariohysterectomy.

OBJECTIVE

To investigate the intraperitoneal (IP) administration of ropivacaine or ropivacaine-dexmedetomidine for postoperative analgesia in cats undergoing ovariohysterectomy.

STUDY DESIGN

Prospective, randomized, blinded, positively controlled clinical study.

ANIMALS

A total of 45 client-owned cats were enrolled.

METHODS

The cats were administered intramuscular (IM) meperidine (6 mg kg) and acepromazine (0.05 mg kg). Anesthesia was induced with propofol and maintained with isoflurane. Meloxicam (0.2 mg kg) was administered subcutaneously in all cats after intubation. After the abdominal incision, the cats were administered one of three treatments (15 cats in each treatment): IP instillation of 0.9% saline solution (group Control), 0.25% ropivacaine (1 mg kg, group ROP) or ropivacaine and dexmedetomidine (4 μg kg, group ROP-DEX). During anesthesia, heart rate (HR), electrocardiography, noninvasive systolic arterial pressure (SAP) and respiratory variables were monitored. Sedation and pain were assessed preoperatively and at various time points up to 24 hours after extubation using sedation scoring, an interactive visual analog scale, the UNESP-Botucatu multidimensional composite pain scale (MCPS) and mechanical nociceptive thresholds (MNT; von Frey anesthesiometer). Rescue analgesia (morphine, 0.1 mg kg) IM was administered if the MCPS ≥6. Data were analyzed using the chi-square test, Tukey test, Kruskal-Wallis test and Friedman test (p < 0.05).

RESULTS

HR was significantly lower in ROP-DEX compared with Control (p = 0.002). The pain scores, MNT, sedation scores and the postoperative rescue analgesia did not differ statistically among groups.

CONCLUSIONS AND CLINICAL RELEVANCE

As part of a multimodal pain therapy, IP ropivacaine-dexmedetomidine was associated with decreased HR intraoperatively; however, SAP remained within normal limits. Using the stated anesthetic protocol, neither IP ropivacaine nor ropivacaine-dexmedetomidine significantly improved analgesia compared with IP saline in cats undergoing ovariohysterectomy.