Canine Stem Cell Factor (SCF) (also known as KIT ligand, KITLG, mast cell growth factor, or steel factor) is a cytokine and growth factor that plays a critical role in hematopoiesis, stem cell maintenance, and immune cell development in dogs (Canis lupus familiaris). SCF belongs to a group of hematopoietic growth factors that regulate the survival, proliferation, and differentiation of stem and progenitor cells. It exerts its biological effects by binding to the c-Kit receptor (CD117), a receptor tyrosine kinase expressed on hematopoietic stem cells, mast cells, melanocytes, and germ cells, activating intracellular signaling pathways including PI3K/AKT, MAPK, and JAK/STAT that promote cell survival, proliferation, and differentiation. In dogs, SCF is produced by stromal cells, fibroblasts, endothelial cells, and epithelial cells, and exists in both membrane-bound and soluble forms, allowing both localized and systemic regulation of c-Kit–expressing cells. Canine SCF is particularly important for mast cell development and survival, making it highly relevant to canine mast cell tumors, one of the most common skin cancers in dogs, where dysregulated c-Kit signaling contributes to abnormal mast cell proliferation. SCF also plays roles in hematopoietic stem cell maintenance, pigmentation, and reproductive cell development. Because of its central role in c-Kit–mediated signaling and stem cell biology, canine SCF is widely studied in veterinary oncology, hematopoiesis, and regenerative medicine, contributing to understanding of mast cell disease and growth factor–regulated cellular development in dogs.