Increased Abundance of Cytotoxic T Cells in Synovial Fluid of a Dog With Erosive Immune‐Mediated Polyarthritis

cytotoxic T cells-while monocyte and B cell counts remained comparable. Treatment with mycophenolate mofetil reduced leukocytes in the synovial fluid and improved the dog's activity, although bone erosion slowly progressed. Based on these findings, we propose that T cells, especially cytotoxic T cells, in synovial fluid contribute to inflammation in canine erosive IMPA and may be a therapeutic target.