Multiple myeloma in cats: Variable presentation with different immunoglobulin isotypes in two cats

Multiple myeloma was diagnosed in two cats with monoclonal hyperglobulinemi a, proteinuria, and plasma cell proliferations in bone marrow. An immunoglo bulin G-producing myeloma occurred in the vertebral bone marrow of one cat, and twice responded to surgical reduction followed by a combination of loc al irradiation and chemotherapy. The cat's survival time was approximately 2 years. The other myeloma in a cat that presented with hypercalcemia and r enal insufficieny involved visceral organs and produced a biclonal peak due to immunoglobulin A dimer formation on serum electrophoresis. This cat's t umor did not respond to chemotherapy.