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Eighteen dogs with monoclonal gammopathies were evaluated retrospectively. Most of the cases were associated with lymphoproliferative tumors (i.e., nine multiple myelomas, one Waldenstrom'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. J Am Anim Hosp Assoc 2002;38:135-147.
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Introduction
Monoclonal gammopathies, also known as paraproteinemias, occur in association with a heterogeneous group of canine diseases that are characterized by an increased proliferation of a single clone of B-cell lymphocytes. This proliferation results in the excessive synthesis of a homogeneous, monoclonal immunoglobulin or a subunit of the immunoglobulin (heavy or light chain). This immunoglobulin or subunit, called paraprotein, can be recognized as a narrow homogeneous band or spike in the electrophoretic pattern of serum, urine, or both. Monoclonal gammopathies are not frequently diagnosed in dogs. The actual prevalence of this increased immunoglobulin production is unknown, but the prevalence of multiple myeloma (the main disease found in association with a monoclonal gammopathy) represents <1% of canine malignant tumors.1 Monoclonal immunoglobulins have also been reported in association with Waldenstrom's macroglobulinemia, chronic lymphocytic leukemia (CLL), lymphoma, nonmyelomatous diseases (i.e., ehrlichiosis, plasmacytic gastroenterocolitis,2 chronic pyoderma3,4), and idiopathic paraproteinemias.5
The purpose of this paper is to compare the clinical, serum biochemical, and hematological findings of the 18 cases, evaluated retrospectively in this study, with those previously described in other reports. Even though some of these findings have already been described, this study presents some interesting and unusual findings: a multiple myeloma with immunoglobulin M (IgM) secretion, another myeloma with two narrow spikes on the electrophoretic pattern, a mucocutaneous plasmacytoma secreting an immunoglobulin G (IgG) paraprotein, a Waldenstrom's macroglobulinemia with an IgM paraprotein having cryoglobulin properties, and a CLL associated with amyloidosis consecutive to the excessive secretion of an IgM paraprotein.
Materials and Methods
Criteria for Selection of the 18 Case Reports
Between 1986 and 1999, 3,925 serum protein...