Description of Ultrasound-Guided Lumbar Erector Spinae Plane (ESP) Block and Comparison of the Spread of Two Volumes of Dye in Cat Cadavers.

The erector spinae plane (ESP) block is a widely used technique for perioperative analgesia. It involves the infiltration of anesthetics into the interfacial plane between the erector spinae muscle and the transverse processes of the vertebrae. In veterinary medicine, this technique has been adapted for different species, but there are no cadaveric studies in cats. This study describes the ultrasound-guided lumbar ESP-block technique and evaluates the spread of two volumes of dye in feline cadavers. Injections were performed at the second lumbar vertebra (L2) level using 0.6 mL/kg (high volume [HV]) and 0.4 mL/kg (low volume [LV]) of methylene blue bilaterally. After anatomical dissection, the distribution of the dye, the staining of the spinal nerve branches, and the presence of dye in the epidural space were recorded. The results demonstrated that the HV treatment provided wider longitudinal distribution, staining the dorsal branch of the spinal nerves in an average of five segments per injection, without extravasation into the epidural space. It is concluded that the HV treatment promotes efficient multisegmental spread in feline cadavers.