Cytokine tear film profile determination in eyes of healthy dogs and those with inflammatory periocular and skin disorders

•Evaluation of tear fluid cytokine levels is relatively simple, painless technique.•IL-2, IL-6, IL-8, and TNF-α were detected in tears >47 % of canine patients.•IL-8 was highest in dogs with both skin and surface ophthalmic disease.•IL-7, IL-10 and IFN-γ were not readily detected in canine tears.•Tear cytokine analysis is useful to investigate local ocular immune responses. Alterations in serum cytokine levels and profiles have been reported in association with a variety of disease conditions (e.g., allergic, immune-mediated, etc.) in both humans and animals. In comparison to serum cytokine measurements, tear cytokine measurements might be expected to more accurately reflect the inflammatory milieu associated with periocular disease. The purpose of this study was to use a multiplexed assay to compare the cytokine profile of tears in healthy dogs to those with inflammatory skin and periocular disease. We were able to detect IL-2, IL-6, IL-8, and TNF-α in >47 % of tear samples from both healthy canine patients and those with inflammatory dermatologic disease (with or without concurrent periocular involvement). In contrast, IL-7, IL-10 and IFN-γ were rarely detected. Dogs with both dermatologic and periocular disease (but not dermatologic disease alone) had higher levels of IL-8 (P 0.05, respectively) relative to healthy dogs. Patients with concurrent dermatologic and periocular disease also demonstrated significantly greater variability in IL-8 concentrations between eyes than did healthy dogs (P