Ferret Interferon-Gamma (IFN-γ) is a type II interferon produced primarily by activated CD4⁺ and CD8⁺ T lymphocytes and natural killer (NK) cells in ferrets (Mustela putorius furo), 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 ferret health and research, IFN-γ is particularly important in models of respiratory viral infections such as influenza virus and SARS-CoV-2, where Th1 responses contribute to viral clearance but may also influence pulmonary inflammation and immunopathology. IFN-γ is also relevant in studies of bacterial infections, vaccine-induced immunity, and T-cell–mediated protection. Because ferrets are widely used as translational models for human respiratory disease and viral transmission, characterization of ferret IFN-γ supports investigations into T-cell immunity, cytokine regulation, vaccine efficacy, and immune-mediated lung pathology, providing valuable comparative insight into cell-mediated immune responses relevant to human infectious disease and immunology research.