Ultrasound-guided axillary approach to the brachial plexus for ulnar osteosynthesis in a lesser anteater (Tamandua tetradactyla): a case report.

An adult lesser anteater (Tamandua tetradactyla), weighing 8.4 kg, was presented for surgical repair of a distal ulnar fracture following a road accident. The aim of this case report was to describe the use of an ultrasound-guided regional anesthetic block in this species, specifically an axillary approach to the brachial plexus, as part of a multimodal analgesic protocol. Premedication included dexmedetomidine (5 µg/kg), ketamine hydrochloride (2 mg/kg), midazolam (0.2 mg/kg), and morphine sulfate (0.2 mg/kg), administered intramuscularly in a single syringe. Anesthetic induction was achieved with propofol (2 mg/kg IV), and anesthesia was maintained with isoflurane via calibrated vaporizer (started at 1.2%) and face mask. Physiological variables were recorded every 10 min using a multiparameter monitor and included heart rate, systolic, diastolic, and mean arterial pressures, respiratory rate, rectal temperature, and peripheral oxygen saturation; serial arterial blood gas analyses were also performed. An ultrasound-guided brachial plexus block using the axillary approach was easily performed, allowing clear visualization of neural and vascular structures and real-time needle guidance. A total volume of 0.4 mL/kg of local anesthetic solution was administered, consisting of bupivacaine 0.5% combined with dexmedetomidine (1 µg/mL), with visualization of local anesthetic spread dorsal to the axillary artery and adjacent to the C8 spinal nerve. The block was performed without complications and was associated with intraoperative cardiovascular stability, suggesting adequate transoperative analgesic efficacy. Although postoperative pain was not assessed using a validated pain scale, no clinical signs consistent with postoperative pain were observed during recovery.