Lateral full-endoscopic lumbosacral foraminotomy for foraminal stenosis in dogs: technique development and initial case series.

Introduction: Degenerative lumbosacral stenosis (DLSS) is a common cause of pain in dogs, with lumbosacral foraminal stenosis (LSFS) frequently contributing to clinical signs through spinal nerve root compression. Conventional surgical approaches for foraminal decompression can be invasive and technically challenging. This study aimed to develop a lateral full-endoscopic lumbosacral foraminotomy (LELF) technique and evaluate its feasibility, safety, and effectiveness in dogs. Methods: LELF was first established in two large-breed dog cadavers, followed by clinical assessment in three dogs diagnosed with LSFS with cross-sectional imaging. Pre- and post-operative assessments included standardized DLSS scoring, owner-reported pain inventory (CBPI), and CT-based neuroforaminal volume measurements. Intra-operative parameters including incision length, surgical time, and visualization quality were recorded. Results: LELF was successfully performed on nine foramina (four cadaveric, five clinical) without conversion to open surgery. Incision length was < 10 mm, median surgical time was 95 min per foramen. All key anatomical landmarks were visualized, and no iatrogenic nerve root injuries occurred. Post-operative CT demonstrated significant enlargement of the lumbosacral foramina (median pre-operative volume: 315.2 mm3; post-operative: 605.6 mm3; Conclusion: LELF is a feasible and minimally invasive technique for LSFS in dogs, achieving effective foraminal decompression and favorable medium-term clinical outcomes. Further studies are warranted to assess long-term efficacy and to compare LELF with open and bi-portal endoscopic approaches.