Case Report: Interlaminar approach for unilateral biportal endoscopy of a thoracolumbar intervertebral disc extrusion in a dog

A 7-year-old castrated male Golden Retriever weighing 41 kg was presented with progressive ambulatory paraparesis and bilateral pelvic limb proprioceptive ataxia (modified Frankel grade 2). Computed tomography and magnetic resonance imaging confirmed a right-ventrolateral T13-L1 intervertebral disc extrusion reducing the cross-sectional area of the spinal cord by approximately 30% at the site of maximal compression. Spinal cord decompression was performed through a unilateral biportal endoscopic interlaminar approach, with the skin entry points of both portals positioned along the medial pedicle line. The interlaminar window was enlarged by partial laminotomy and partial medial facetectomy while preserving the pedicle and the majority of the articular processes joint. The wide dorsal endoscopic view provided direct visualization of an adherent, encapsulated disc fragment and an adjacent congested internal vertebral venous sinus facilitating their management. The dog recovered uneventfully from anesthesia. Mild residual left pelvic limb monoparesis was present at discharge and, at the final evaluation on postoperative day 109 (modified Frankel grade 2), at which time the paw placement response was normal in the right pelvic limb and intermittently mildly delayed in the left pelvic limb. No recurrence of clinical signs was reported by the owner on postoperative day 121. To the authors' knowledge, this is the first clinical report of an interlaminar unilateral biportal endoscopic approach for canine thoracolumbar intervertebral disc extrusion, broadening the minimally invasive options for this condition.