Equine CCL3 (C-C motif chemokine ligand 3, also known as MIP-1α, macrophage inflammatory protein-1 alpha) is a pro-inflammatory chemokine that regulates recruitment and activation of immune cells during inflammatory and infectious responses in horses (Equus caballus). CCL3 primarily signals through the CCR1 and CCR5 receptors, promoting chemotaxis of monocytes, macrophages, dendritic cells, natural killer (NK) cells, and activated T lymphocytes to sites of infection or tissue injury. In horses, CCL3 is produced by activated macrophages, epithelial cells, endothelial cells, and lymphocytes in response to inflammatory stimuli such as microbial components and cytokines including TNF-α and IL-1β. CCL3-mediated immune cell recruitment contributes to host defense in conditions such as equine respiratory infections (including equine influenza and bacterial pneumonia), inflammatory airway disease, and musculoskeletal inflammation, where infiltration of monocytes and T cells supports immune activation and tissue repair. However, excessive or prolonged CCL3 expression may contribute to persistent inflammation and tissue damage in chronic inflammatory conditions such as equine asthma or joint inflammation. As a regulator of leukocyte trafficking and inflammatory signaling, equine CCL3 is important in studies of host–pathogen interactions, respiratory disease, and inflammatory mechanisms affecting equine health and performance.