Ultrasound-guided transversus abdominis plane block in the dog: An anatomical evaluation

Objective To describe the ultrasound-guided technique to the transversus abdominis plane (TAP) block in the dog and evaluate the spread of a local anesthetic/methylene blue solution. Study design Prospective experimental trial. Animals Ten adult Beagle cadavers weighing 11.1± 1.1kg (mean±SD). Methods Transversus abdominis plane (TAP) blocks were performed bilaterally by a single trained individual on unpreserved cadaver dogs using 10mL of methylene blue/bupivacaine solution per site. Dissection of the abdominal wall was performed within 15-55minutes of block to determine distribution of injectate and nerve involvement in the transversus abdominis fascial plane. Results The transversus abdominis fascial plane was adequately visualized via ultrasound and injected in twenty hemi-abdominal walls. Segmental branches of T11, T12, T13, L1, L2, and L3 were adequately stained in 20%, 60%, 100%, 100%, 90%, and 30% of injections, respectively. Conclusions and clinical relevance This anatomical study suggests that the transversus abdominis plane (TAP) block would provide adequate regional anesthesia of the abdomen, potentially extending to the cranial and caudal limits of the abdomen. This supports the clinical potential of this block in veterinary medicine.