Canine 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 dogs (Canis lupus familiaris). 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, proteins that regulate immune signaling, apoptosis, and inflammatory pathways. In dogs, 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 canine health, TNF-α is involved in immune responses to bacterial infections, viral diseases, and inflammatory conditions, including canine parvovirus infection, leishmaniasis, and chronic inflammatory disorders such as inflammatory bowel disease (IBD). Elevated TNF-α levels are also associated with sepsis, autoimmune diseases, and cancer-related inflammation, where dysregulated TNF signaling can contribute to tissue damage and disease progression. Because TNF-α is a key mediator of inflammation and immune regulation, canine TNF-α is widely studied in veterinary immunology, infectious disease research, and inflammatory disease models, contributing to improved understanding of immune responses and potential therapeutic strategies in dogs.