Multiple myeloma in a dog: a typical presentation with an atypical serum protein electrophoretogram

Abstract

A nine-year-old spayed female labrador retriever presented with marked paraparesis. Radiographic imaging revealed regions of osteolysis within the spinous process of the L1 vertebra and the lamina and pedicles of the T13 vertebra. Cytological examination of the bone marrow exhibited a marked increase in plasma cells; histopathology of a core needle biopsy from the L1 spinous process revealed normal bone marrow findings with only scattered plasma cells. The serum biochemical profile demonstrated multiple abnormalities, some of which are frequently observed in cases of multiple myeloma such as hypercalcaemia and hyperglobulinemia. Initial serum protein electrophoresis (SPE) exhibited a tall, narrow peak of the β-1 region superimposed onto a broad total β globulin base. The SPE also demonstrated a second α-2 spike and low γ fraction. Although a urinalysis revealed a significant proteinuria, the patient lacked a Bence Jones proteinuria. The combined diagnostic workup was consistent with multiple myeloma.