Cerebrospinal Fluid Cytokine and Chemokine Analysis in Dogs With Meningoencephalitis of Unknown Origin or Idiopathic Epilepsy

Background Current diagnosis of brain disease in dogs is dependent on imaging and cerebrospinal fluid (CSF) analysis, including total nucleated cell counts and albumin concentrations. Hypothesis/Objectives To determine whether multiplex cytokine/chemokine (Ct/Cm) analysis can differentiate among dogs with meningoencephalitis of unknown origin (MUE), idiopathic epilepsy (IE), and brain neoplasia. Animals Client owned dogs diagnosed with brain disease with MRI and CSF diagnostics. Groups included 18 dogs with a diagnosis of MUE, 21 dogs with IE, and 7 dogs with brain tumors. Methods A retrospective observational study; a multiplex immunoassay was utilized to measure CSF concentrations for the following: Interleukin (IL)‐2, IL‐6, IL‐7, IL‐8, IL‐10, IL‐15, and IL‐18, granulocyte macrophage colony‐stimulating factor (GM‐CSF), interferon gamma (IFN‐γ), keratinocyte chemoattractant (KC)‐like protein, IFN‐γ‐inducible protein‐10 (IP‐10), monocyte chemotactic protein 1 (MCP‐1), and tumor necrosis factor alpha (TNF‐α). Results Several Ct/Cm were detected only in MUE cases: GM‐CSF (9/18), IFN‐γ (13/18), IL‐2 (8/18), IL‐15 (4/18), and TNF‐α (11/18). Other Ct/Cm concentrations were significantly higher in MUE cases (IL‐8: median 101 pg/mL, range 144, p = 0.019; IL‐18: median 3 pg/mL, range 0.52, p < 0.001; MCP‐1: median 814 pg/mL, range 1319, p = 0.004; and IL‐6: median 5 pg/mL, range 16, p < 0.001) compared to epilepsy and neoplasia. Conclusions and Clinical Importance IFN‐γ, TNF‐α, GM‐CSF, IL‐2, and IL‐15 might be specific markers of MUE in canine CSF and could be potentially useful biomarkers in the diagnosis of MUE.