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Background: Hyperglobulinemia is reported in 26% of canine chronic B‐cell lymphocytic leukemia (B‐CLL) cases. However, few cases have been characterized by protein electrophoresis and immunofixation (IF), and the incidence of a monoclonal protein (M‐protein) is unknown using these techniques. Objective: To characterize and determine the proportion of canine B‐CLL cases with an M‐protein using plasma protein electrophoresis (PPE), routine and free light chain (fLC) IF, and to assess if productive B‐CLL cases express MUM1/IRF4 by cell tube block (CTB). Methods: PPE, routine (targeting IgG, IgA, IgM, IgG4, and light chain) and fLC IF were performed using 48 dog B‐CLL plasma samples from patients diagnosed via peripheral blood flow cytometry. CTB was performed on a separate cohort of 15 patients. Results: Hyperproteinemia (>7.5 g/dL) was present in 17/48 cases (35%). An M‐protein was detected in 32/48 cases (67%). Of these, 19/32 cases (59%) had only complete (monoclonal heavy and light chain) M‐proteins detected, 10/32 cases (31%) had both complete and fLC M‐proteins detected, and 3/32 cases (9%) had only an fLC M‐protein detected. IgM was the most common clonal immunoglobulin isotype detected (23 cases). CD21+ cell counts were higher in cases with detectable M‐protein. Plasma fLC IF suggested β‐γ region interference, likely caused by clotting proteins. All B‐CLL cases consistently expressed PAX5 and did not express MUM1/IRF4. Conclusions: Most B‐CLL cases had an M‐protein and were not hyperproteinemic. Most cases with paraproteins had a complete IgM monoclonal gammopathy; a subset had documented fLCs. The prognostic significance of heavy and fLC presence should be evaluated. [ABSTRACT FROM AUTHOR]

A 13‐year‐old spayed female American Cocker Spaniel was presented for evaluation of a cough and weight loss. Physical exam revealed generalized lymphadenopathy. The patient was diagnosed with marginal zone lymphoma (MZL) on histopathology of an extirpated lymph node. This report demonstrates an unusual case of a pleomorphic neoplastic population documented on cytologic evaluation that had moncytoid features and peripheral blood involvement; a previously undocumented IgG1 monoclonal gammopathy was also an interesting feature of this canine MZL. The patient did not undergo chemotherapy for lymphoma and was euthanized over 4 years after the initial presentation. [ABSTRACT FROM AUTHOR]

Background Electrophoretic analysis of plasma may provide inaccurate results unless plasma is defibrinated with ethanol. Objective The aim of this study, conducted following the Standards for Reporting of Diagnostic Accuracy ( STARD), was to determine whether cellulose acetate ( CAE), agarose gel ( AGE), and capillary zone ( CZE) electrophoresis of native plasma ( NP) and defibrinated plasma ( DP) provided the same information as serum electrophoretograms. Methods Serum, NP, and DP electrophoretograms obtained using the 3 methods were examined visually by 3 observers to identify changes in globulin fractions and provide diagnostic interpretations. Using serum analysis as the reference method, sensitivity, specificity, and positive likelihood ratio of NP and DP electrophoretograms to identify abnormal globulin profiles were calculated. Results Specimens from 46 dogs were analyzed. Albumin and α1- and γ-globulin fractions were lower and β2-globulin fractions higher in NP than in serum and DP. Interpretations of NP electrophoretograms were the same as for serum in 54.8% ( CAE), 51.2% ( AGE), and 51.6% ( CZE), revealed an increased β-globulin fraction in 32.3-41.5%, and resulted in misinterpretation, especially for CZE analysis, in 4.7-16.1% of the dogs; all dogs with abnormal serum electrophoretograms were identified correctly using NP. Analysis of DP was similar to serum analysis in about 2/3 of the dogs. In the others, defibrination did not resolve spurious plasma findings or induced additional changes. Up to 75 and 27% of NP and DP electrophoretograms, respectively, were abnormal in dogs with normal serum electrophoretograms. Sensitivity for NP and DP analysis was high, but specificity for NP was poor. Conclusions Analysis of NP provides the same information as serum analysis in > 50% of cases, and, despite low specificity, could preliminarily exclude the presence of abnormalities when only plasma is available. If electrophoretograms are not normalized by defibrination, electrophoretic abnormalities are likely present, and electrophoresis should be repeated using serum. [ABSTRACT FROM AUTHOR]