Swine CXCL9 (C-X-C motif chemokine ligand 9), also known as MIG (monokine induced by interferon-γ), is a proinflammatory chemokine belonging to the CXC chemokine family, which also includes CXCL10 (IP-10) and CXCL11 (I-TAC) that regulate T-cell recruitment during interferon-driven immune responses. In pigs (Sus scrofa), CXCL9 is produced by macrophages, dendritic cells, endothelial cells, and epithelial cells in response to interferon-γ (IFN-γ) and inflammatory stimuli during infection or immune activation. CXCL9 signals primarily through the chemokine receptor CXCR3, expressed on activated T lymphocytes, natural killer (NK) cells, and other immune cells, promoting chemotaxis and accumulation of these cells at sites of infection or inflammation. In swine health, CXCL9 contributes to Th1-type immune responses against intracellular pathogens, particularly in tissues such as the lung and lymphoid organs during viral and bacterial infections. Pigs are also used as translational animal models for human respiratory and infectious diseases, including influenza virus infection, where CXCL9 is part of the interferon-driven chemokine network that recruits CXCR3⁺ T cells to infected lung tissue, helping regulate antiviral immunity and inflammatory responses relevant to both veterinary and human biomedical research.