The cytokines in serum such as interleukin-4 (IL-4), IL-6, IL-17, tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) also act as indirect indexes in inflammatory conditions [7], which suggests that beside SCC and SCS, serum cytokines could be considered as crucial indicators for bovine mastitis. Here, IL4 is linked to mastitis.