Long-term clinical and functional outcome following extensive left-sided epaxial muscle resection (T13-L7) for a longissimus lumborum liposarcoma in a dog – case report

Background Liposarcomas are uncommon malignant soft tissue sarcomas in dogs and intramuscular liposarcomas involving the epaxial musculature are rare. Due to their locally invasive nature, wide excision has historically been recommended however, the functional outcome following extensive epaxial muscle resection in dogs has not been documented. Case presentation A 10-year-old male-neutered Border Collie presented with a large, slowly progressive left dorsal lumbar swelling. Computed tomography identified a heterogeneous intramuscular mass within the left longissimus lumborum muscle extending from L1 to L6, with no evidence of metastatic disease. Cytology was consistent with liposarcoma. Surgery was performed via unilateral marginal excision of the multifidus, longissimus lumborum, and iliocostalis lumborum muscles. Significant hemorrhage and transient hypotension required blood transfusion and intensive care. Histopathology confirmed a well-differentiated liposarcoma. Transient hindlimb weakness and compensatory scoliosis was identified during postoperative recovery which improved over time. The dog returned to normal activity with no evidence of local recurrence, based solely on physical examination at 16-month follow-up. Conclusions This case suggests that extensive unilateral lumbar epaxial muscle resection can result in acceptable perioperative morbidity and excellent long-term functional outcome. Extensive unilateral epaxial muscle excision may represent a viable treatment option for selected paraspinal soft tissue sarcomas, supporting good quality of life despite substantial muscle loss.