Anatomical evaluation and cone-beam computed tomography of some maxillary nerve block approaches in dog

Effective pain management is a cornerstone of modern veterinary surgical care, with regional nerve blocks as a crucial tool for targeted analgesia. The maxillary nerve, a major sensory branch of the trigeminal nerve, innervates numerous facial and oral structures, making its blockade essential in oral and maxillofacial procedures in dogs. Despite several described approaches namely the subzygomatic, infraorbital, and maxillary tuberosity techniques, there remains limited comparative anatomical and radiological data to guide clinical decision-making. This study evaluated these three approaches using anatomical dissection and cone-beam computed tomography (CBCT) in six canine cadavers (n = 6). Each received an injectate (methylene blue, iohexol, and bupivacaine) via the three techniques. Pre- and post-injection CBCT scans were analyzed using NNT Viewer v3 and OnDemand3D software, measuring contrast spread in sagittal and dorsal planes (1- and 10-mm slices) and correlating with dissections. Results demonstrated that the infraorbital approach had significantly higher staining of the maxillary nerve compared to the maxillary tuberosity and subzygomatic approaches (P < 0.05). The maximum amount of diffusion of the contrast medium along the maxillary nerve was for the infraorbital approach. Sagittal (10 mm) and dorsal (1 mm) sections had the highest compliance with the length of dye diffusion measured in the anatomical sections. In the maxillary tuberosity approach, sagittal and dorsal views with a thickness of 10 mm had the highest compliance with the length of dye diffusion measured in the anatomical sections. The infraorbital method provided the most consistent and effective blockade, suggesting its preferential use in clinical practice for optimized analgesia.