A 3.5-year-old neutered female, Alaskan Malamute, dog was presented to our hospital with a primary complaint of recurrent vomiting. A liver mass was observed on radiography and ultrasonography; however, gastroscopy was seemingly not associated with the vomiting. Computed tomography (CT) scan confirmed compression of the gastric pylorus due to enlarged liver lymph nodes, which was then determined to the cause of the vomiting. In addition, a round nodule was present in the spleen, with suspected lung, intrathoracic and intraperitoneal lymph node metastasis. Histopathologic examination of the liver mass biopsy showed malignant histiocytes. Furthermore, immunohistochemistry staining using Vimentin, Iba-1, alpha-smooth muscle actin (α-SMA), and Masson’s Trichrome staining confirmed that the neoplastic cells were of histiocyte and myofibroblast origin. After the histopathological diagnosis, the patient received hospice care, and euthanasia was performed 52 days after the first visit.