Swine Leukemia Inhibitory Factor (LIF) is a multifunctional cytokine belonging to the IL-6 family—which includes IL-6, IL-11, oncostatin M (OSM), ciliary neurotrophic factor (CNTF), cardiotrophin-1 (CT-1), cardiotrophin-like cytokine factor 1 (CLCF1), and IL-27—and signals through receptor complexes containing the shared gp130 subunit. In pigs (Sus scrofa domesticus), LIF binds to the LIF receptor (LIFR) in association with gp130, activating JAK/STAT3, MAPK, and PI3K signaling pathways that regulate cell survival, differentiation, immune modulation, and tissue repair. Swine LIF plays important roles in reproductive biology, including endometrial receptivity, conceptus development, and embryo implantation, making it highly relevant to fertility management and assisted reproductive technologies in commercial swine production. LIF is also involved in hematopoiesis, stem cell regulation, and modulation of inflammatory responses during respiratory and enteric infections such as porcine reproductive and respiratory syndrome virus (PRRSV) and swine influenza, where STAT3-mediated signaling can influence tissue remodeling and immune balance. Dysregulated LIF expression may contribute to fibrosis or tumor progression in certain contexts. As both a regenerative and immunomodulatory cytokine, swine LIF is important in studies of reproductive efficiency, vaccine responses, inflammatory disease mechanisms, and translational large-animal models. Characterization of swine LIF supports comparative research into IL-6 family signaling and development of STAT3-targeted therapeutic strategies relevant to both veterinary and human medicine.