Monoclonal gammopathies in the dog: a retrospective study of 18 cases (1986-1999) and literature review.

Eighteen dogs with monoclonal gammopathies were evaluated retrospectively. Most of the cases were associated with lymphoproliferative tumors (i.e., nine multiple myelomas, one Waldenström's macroglobulinemia, one lymphoma, one chronic lymphocytic leukemia, and one mucocutaneous plasmacytoma). The prevalence of nonmyelomatous monoclonal gammopathies (28%) was also significant (three leishmaniasis and two ehrlichiosis). Presenting complaints and clinical signs often were nonspecific or related to bleeding diathesis. Significant laboratory findings included proteinuria, hypoalbuminemia, and anemia. Some unusual features were also observed: a multiple myeloma with immunoglobulin M secretion, another myeloma with two narrow spikes on the electrophoretic pattern, and a mucocutaneous plasmacytoma secreting an immunoglobulin G paraprotein.