Canine Interleukin-12 p70 (IL-12 p70) is a heterodimeric cytokine that plays a central role in regulating cell-mediated immune responses in dogs (Canis lupus familiaris). IL-12 p70 is composed of two subunits, p35 and p40, and is produced primarily by activated antigen-presenting cells such as macrophages and dendritic cells in response to microbial infection or inflammatory stimuli. Canine IL-12 p70 binds to the IL-12 receptor complex expressed on natural killer (NK) cells and T lymphocytes, activating intracellular signaling through the JAK–STAT pathway, particularly STAT4, which promotes differentiation of naïve T cells into T helper 1 (Th1) cells. This signaling enhances production of interferon-γ (IFN-γ), increases cytotoxic activity of NK cells, and strengthens cell-mediated immunity against intracellular pathogens. In dogs, IL-12 p70 contributes to host defense against bacterial, viral, and parasitic infections and plays an important role in regulating inflammatory immune responses. Canine IL-12 p70 is also studied in translational biomedical research; for example, canine models of osteosarcoma and melanoma are used to investigate IL-12–based immunotherapies, where IL-12-mediated activation of anti-tumor immune responses helps evaluate therapeutic strategies that may inform both veterinary cancer treatment and human oncology.