Guinea Pig 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 guinea pigs (Cavia porcellus), CXCL9 is produced by macrophages, dendritic cells, endothelial cells, and epithelial cells in response to interferon-γ (IFN-γ) and other 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 recruitment of these cells to sites of infection or inflammation. In guinea pig immunity, CXCL9 contributes to Th1-type cell-mediated immune responses against intracellular pathogens, particularly in the lung and lymphoid tissues. Guinea pigs are widely used as animal models for tuberculosis caused by Mycobacterium tuberculosis because their pulmonary pathology closely resembles human disease, and CXCL9 participates in the interferon-driven chemokine network that recruits T cells to granulomatous lesions in infected lung tissue. These models make guinea pig CXCL9 important for studying T-cell trafficking, granuloma formation, and host immune responses in mycobacterial infections.