Tumor cells from four dogs weakly expressed CD5, but the cells in three of these four dogs expressed other myeloid antigens, such as CD11b, and all had strong positive reactions for ALP or other myeloid enzymes (diffuse light or chunky ANBE, CAE) and were negative for CD3 and TCRαβ, supporting a diagnosis of AML over acute lymphoid leukemia (ALL). The gene discussed is CD5; the disease is acute myeloid leukemia.