Feline Tumor Necrosis Factor Alpha (TNF-α) (also known as TNF or cachectin) is a proinflammatory cytokine that plays a central role in innate immune responses, inflammation, and host defense against pathogens in cats (Felis catus). TNF-α is a member of the tumor necrosis factor (TNF) superfamily, which includes related cytokines such as TNF-β (lymphotoxin-α), Fas ligand (FasL), CD40 ligand (CD40L), and TRAIL, molecules that regulate immune signaling, apoptosis, and inflammatory processes. In cats, TNF-α is primarily produced by activated macrophages, monocytes, dendritic cells, and T lymphocytes in response to infection, tissue injury, or inflammatory stimuli. TNF-α exerts its biological effects by binding to TNF receptors TNFR1 (p55) and TNFR2 (p75), activating intracellular signaling pathways including NF-κB, MAPK, and caspase-mediated pathways, which regulate cytokine production, immune cell activation, apoptosis, and inflammatory responses. In feline health, TNF-α is involved in immune responses to viral infections such as feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV), as well as bacterial infections, inflammatory diseases, and cancer. Dysregulated TNF-α production can contribute to chronic inflammation and tissue damage, making it an important mediator of inflammatory pathology. Because TNF-α plays a key role in immune regulation and inflammatory disease, feline TNF-α is studied in veterinary immunology, infectious disease research, and inflammatory disorder models, helping to improve understanding of immune responses and disease mechanisms in cats.