Canine CCL4 (C-C motif chemokine ligand 4, also known as MIP-1β, macrophage inflammatory protein-1 beta) is a pro-inflammatory chemokine that plays an important role in recruitment and activation of immune cells during inflammatory and antiviral immune responses in dogs (Canis lupus familiaris). CCL4 primarily signals through the CCR5 receptor, promoting chemotaxis of monocytes, macrophages, dendritic cells, natural killer (NK) cells, and activated T lymphocytes to sites of infection or tissue injury. In dogs, CCL4 is produced by activated macrophages, dendritic cells, epithelial cells, and lymphocytes in response to inflammatory stimuli such as microbial components and cytokines including TNF-α and IL-1β. CCL4-mediated leukocyte recruitment contributes to host defense in infectious diseases such as canine distemper virus, parvovirus infection, and bacterial infections, where coordinated immune cell trafficking supports pathogen clearance. CCL4 is also implicated in chronic inflammatory and immune-mediated conditions, including dermatitis and inflammatory bowel disease, as well as in canine cancers such as lymphoma, where chemokine signaling can influence immune cell infiltration within the tumor microenvironment. While CCL4-driven leukocyte migration is important for immune activation and pathogen defense, excessive or prolonged expression may contribute to tissue inflammation and damage. As a regulator of immune cell trafficking and inflammatory signaling, canine CCL4 is important for studies of host–pathogen interactions, immune regulation, and inflammatory disease mechanisms relevant to both veterinary medicine and comparative immunology.