Bovine 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 cattle (Bos taurus). 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 cattle, 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 immune cell recruitment plays an important role in host defense against pathogens involved in diseases such as bovine respiratory disease complex (BRDC), mastitis, and mycobacterial infections including Mycobacterium bovis. In these conditions, infiltration of monocytes and lymphocytes contributes to pathogen clearance and activation of adaptive immune responses. However, excessive or prolonged expression of CCL4 may contribute to inflammatory tissue damage and chronic inflammation. As a regulator of leukocyte trafficking and inflammatory signaling, bovine CCL4 is important for studies of host–pathogen interactions, inflammatory disease mechanisms, and vaccine responses aimed at improving immune protection and disease resistance in cattle.