Equine CCL2 (C-C motif chemokine ligand 2, also known as monocyte chemoattractant protein-1, MCP-1) is a pro-inflammatory chemokine that plays a key role in recruitment and activation of monocytes, macrophages, and memory T cells during immune responses in horses (Equus caballus). CCL2 signals primarily through the CCR2 receptor, activating intracellular pathways that promote leukocyte migration, cytokine production, and coordination of innate and adaptive immune responses at sites of infection, inflammation, or tissue injury. In equine health, CCL2 is particularly important in inflammatory conditions such as equine asthma (recurrent airway obstruction), osteoarthritis, laminitis, and infectious diseases, where monocyte and macrophage recruitment contributes to tissue inflammation and repair. CCL2-mediated signaling also plays a role in joint inflammation by promoting infiltration of immune cells into synovial tissues during degenerative joint disease. While CCL2-driven immune cell trafficking is essential for pathogen defense and wound healing, excessive or chronic expression can contribute to persistent inflammation and tissue damage. As a biomarker of monocyte/macrophage recruitment and inflammatory activation, equine CCL2 is widely studied in investigations of respiratory disease, musculoskeletal injury, and immune responses to infection. Characterization of equine CCL2 supports veterinary research into inflammatory disease mechanisms, host–pathogen interactions, and development of targeted therapies to improve equine health and performance.