Bilateral Ultrasound-Guided Transversus Thoracic Plane Block as Part of a Multimodal Analgesic Plan in Two Rabbits Undergoing Median Sternotomy.

Two client-owned Lionhead rabbits underwent median sternotomy for mediastinal mass excision. Premedication included methadone, dexmedetomidine, and midazolam, with ketamine added for one rabbit. Anesthesia was maintained with isoflurane in oxygen and a ketamine infusion. Bilateral ultrasound-guided TTP blocks were performed at the level of the second and fifth intercostal spaces using a linear transducer and a spinal needle advanced in-plane in a lateromedial direction. Bupivacaine 0.5% was injected at a total dose of 2 mg/kg per rabbit, divided equally among four injection sites (total volumes of 0.9 mL and 1.0 mL for the first and second rabbits, respectively). Only one rabbit exhibited a brief intraoperative nociceptive response. The second rabbit developed severe postoperative respiratory compromise related to inadequate thoracic drain function and died 4 h after surgery. These cases indicate that the TTP block is technically feasible in rabbits and can contribute to intraoperative analgesia during thoracic surgery. Further studies are needed to evaluate the optimal injectate volume and its distribution, as well as the safety and efficacy of the anesthetic dose.