Monoclonal gammopathy without hyperglobulinemia in 2 dogs with IgA secretory neoplasms.

Two dogs, an 8.5-year-old intact male Golden Retriever and a 10-year-old spayed female English Springer Spaniel, each with varied clinical histories, were referred to the Colorado State University Veterinary Teaching Hospital for evaluation of hypercalcemia and severe anemia, respectively. In each dog, serum total protein and globulin concentrations were within reference intervals. Cytologic examination of bone marrow aspirates from both dogs revealed moderate to marked numbers of atypical lymphoid cells with plasma cell features. Using serum immunofixation and serum immunoglobulin (Ig) quantification, a monoclonal Ig protein was identified. In conjunction with other clinicopathologic and molecular findings, IgA secretory neoplasms, B-cell lymphoma with plasmacytoid features and multiple myeloma (MM), were diagnosed. To our knowledge, these cases represent the first descriptions of IgA-secreting neoplasms in dogs that lacked hyperglobulinemia. In cases of suspected B-cell lymphoma or MM in dogs, serum proteins should be fully evaluated for the presence of a monoclonal Ig even in dogs that lack characteristic hyperproteinemia or hyperglobulinemia. This evaluation will aid in the diagnosis of secretory B-cell lymphoma or MM leading to appropriate clinical and therapeutic case management.