A Modified Approach for the Ultrasound-Guided Quadratus Lumborum Block in Dogs: A Cadaveric Study

SIMPLE SUMMARY: This study describes a modified approach for the ultrasound-guided quadratus lumborum block in dogs. Previous studies carried out in canine cadavers describe the needle insertion following a ventro-lateral to dorso-medial approach. Our modified technique follows a dorso-lateral to ventro-medial direction. We aimed to have the same success with this approach as previous studies in dogs but to minimise the potential complications. After performing the modified technique bilaterally in nine canine cadavers and administering contrast, we assessed the contrast distribution with computed tomography (CT) and dissection. Potential complications were also assessed. Our dissection results showed similar distribution to previous studies, although CT results showed a more caudal contrast spreading. No contrast was found in the abdomen or epidural space. This study shows that our modified approach is safe and has at least the same distribution as the previous studies published in dogs. ABSTRACT: Ultrasound-guided quadratus lumborum block (QLB) is a locoregional technique described in canine cadavers. The aim of this study was to assess a modified approach to QLB to minimise potential complications such as abdominal organ puncture. Nine canine cadavers were included and were positioned in lateral recumbency. An ultrasound-guided QLB was performed on each side. The probe was placed in the transverse position over the lumbar muscles just caudal to the last rib, and a needle was advanced in-plane from a dorso-lateral to a ventro-medial. A volume of 0.2 mL kg(−1) of a mixture of iomeprol and methylene blue was injected. Computed tomography (CT) and dissection were performed to evaluate the spreading. Success was defined as staining of the nerve with a length of more than 0.6 cm. Potential complications such as intra-abdominal, epidural, or intravascular spreading of the mixture were also assessed. The CT images showed a T13 to L7 vertebra distribution, with a median of 5 (3–6). Dissection showed staining of the nerves from T13 to L4, with a median of 3 (2–5). No complications were found. This modified approach to QLB is safe and shows similar results to the previous studies in canine carcass.