Monoclonal gammopathy in a dog with chronic pyoderma

A monoclonal gammopathy composed of immunoglobulin G, with concurrent light‐chain proteinuria and generalized lymph node plasmacytosis, was associated with chronic pyoderma in a dog. A uniform population of plasma cells was observed cytologically and histologically in multiple lymph node specimens. A diagnosis of monoclonal gammopathy of unknown significance was eventually made by exclusion of other known causes of monoclonal gammopathy, resolution after antibiotic therapy, and no evidence of lymphoproliferative disease after 11 months of follow‐up and subsequent necropsy. This report expands the diagnostic considerations for monoclonal gammopathies in the dog.