Transversus abdominis plane block using liposomal or bupivacaine hydrochloride with dexmedetomidine provides comparable analgesia to high-dose intravenous buprenorphine in pigs.

Abstract

Objective: To evaluate the efficacy of bilateral transversus abdominis plane (TAP) blocks using either liposomal bupivacaine (2.66 mg/kg) expanded with bupivacaine hydrochloride (HCl; 0.5%; 2 mg/kg) or bupivacaine HCl (0.5%; 2 mg/kg), each combined with dexmedetomidine (0.4 μg/kg), for abdominal wall desensitization in pigs compared to high-dose IV buprenorphine (0.1 mg/kg).

Methods: A prospective, randomized, blinded study was conducted in 24 pigs assigned to 1 of 3 treatment groups: (1) saline TAP block and 0.1 mg/kg IV buprenorphine, (2) TAP block with bupivacaine HCl (0.5%; 2 mg/kg) and dexmedetomidine (0.4 μg/kg), and (3) TAP block with liposomal bupivacaine (2.66 mg/kg) admixed with bupivacaine HCl (0.5%; 2 mg/kg) and dexmedetomidine (0.4 μg/kg). Transversus abdominis plane blocks were administered at 0.8 mL/kg/hemiabdomen (1.6 mL/kg total/pig). Skin sensitivity was assessed using forceps testing at baseline and at 6, 12, 24, 48, 72, and 96 hours after block using a predefined scoring system. The primary outcome was time to resensitization.

Results: All TAP blocks were technically successful. Peak desensitization occurred at 6 hours in all groups. No significant differences in the duration or extent of nociceptive blockade were observed between treatments. This study represents the first in vivo assessment of TAP block efficacy in pigs.

Conclusions: Liposomal bupivacaine admixed with bupivacaine HCl and dexmedetomidine did not provide prolonged analgesia compared to bupivacaine HCl with dexmedetomidine or high-dose IV buprenorphine.

Clinical relevance: TAP blocks may reduce reliance on systemic opioids, supporting opioid-sparing pain management strategies in veterinary medicine.