Feline Interferon-Gamma (IFN-γ) is a type II interferon produced primarily by activated CD4⁺ and CD8⁺ T lymphocytes as well as natural killer (NK) cells in cats (Felis catus), where it plays a central role in cell-mediated (Th1-type) immunity. IFN-γ signals through the IFN-γ receptor complex (IFNGR1/IFNGR2), activating JAK/STAT1 pathways and inducing genes involved in macrophage activation, enhanced antigen presentation via upregulation of MHC class I and II molecules, and promotion of cytotoxic T-cell responses. In feline health, IFN-γ is critical for host defense against intracellular pathogens and viral infections such as feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), feline infectious peritonitis (FIP; feline coronavirus), Toxoplasma gondii, and mycobacterial infections, where balanced Th1 responses contribute to pathogen control while dysregulation may influence immunopathology or chronic inflammation. Clinically, IFN-γ expression levels serve as indicators of cellular immune competence and disease progression. In animal model research, cats serve as important natural models for human retroviral infection (FIV as a model for HIV), coronavirus-associated immune dysregulation (FIP as a model for severe systemic coronavirus disease), and certain immune-mediated and oncologic conditions. Characterization of feline IFN-γ supports studies of antiviral immunity, T-cell function, vaccine development, and comparative Th1 immune regulation, enhancing translational understanding of cell-mediated immune responses relevant to both veterinary and human medicine.