Ovine CCL4 (C-C motif chemokine ligand 4, also known as MIP-1β, macrophage inflammatory protein-1 beta) is a pro-inflammatory chemokine that regulates recruitment and activation of immune cells during inflammatory and infectious responses in sheep (Ovis aries). 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, inflammation, or tissue injury. In sheep, 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 against pathogens involved in diseases such as ovine respiratory infections, mastitis, and parasitic diseases common in small ruminants, where infiltration of monocytes and lymphocytes supports pathogen clearance and immune activation. While CCL4-driven leukocyte trafficking supports protective immune responses and tissue repair, excessive or prolonged expression may contribute to chronic inflammation and tissue damage. As a regulator of immune cell migration and inflammatory signaling, ovine CCL4 is important for studies of host–pathogen interactions, inflammatory disease mechanisms, and immune responses relevant to sheep health and small ruminant veterinary research.