A five-year-old female boxer presented with a swelling in the area of the caudal mammary gland. The mass was surgically excised and histopathological examination revealed a poorly demarcated lesion, extending into mammary tissue and infiltrating the sinuses of adjacent lymph nodes. The diagnosis was lymphangiosarcoma. Full blood work, thoracic radiographs, abdominal and scar ultrasound were unremarkable, apart from possible inflammatory reactions in the latter and reactive/metastatic changes in inguinal lymph nodes. Doxorubicin treatment resulted in a 6-month recurrence free interval. At relapse, the dog was treated with metronomic chemotherapy using chlorambucil and meloxicam, which failed to adequately control the disease. Toceranib phosphate was introduced and resulted in almost complete regression of the mass, leaving just a skin plaque. To the authors’ knowledge this is the first report describing the use of two novel therapeutic approaches to treat canine lymphangiosarcoma that resulted in a higher than previously described survival time.