Canine CCL19 (C-C motif chemokine ligand 19), also known as macrophage inflammatory protein-3β (MIP-3β) or EBI1 ligand chemokine (ELC), is a member of the CC chemokine family that plays a central role in lymphocyte trafficking and organization of secondary lymphoid tissues in dogs (Canis lupus familiaris). CCL19 is produced primarily by stromal cells, dendritic cells, and macrophages within lymph nodes, spleen, and other lymphoid structures. It functions through the CCR7 receptor to direct migration of naïve T cells, central memory T cells, and mature dendritic cells to lymphoid tissues, facilitating antigen presentation and initiation of adaptive immune responses. In healthy dogs, CCL19 supports immune surveillance and maintenance of lymphoid architecture; however, expression may increase during infection, vaccination, chronic inflammation, or neoplastic disease. In veterinary and comparative medicine research, canine CCL19 is of particular interest in studies of vaccine responses, immune-mediated diseases, lymphoma and other lymphoid malignancies, and infectious diseases such as canine distemper virus and leishmaniasis. Characterization of CCL19 in dogs provides valuable insight into CCR7-mediated immune cell trafficking, lymphoid tissue organization, and adaptive immune regulation in both veterinary and translational research contexts.