Canine 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 dogs (Canis lupus familiaris). 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 canine health, CCL2 is particularly important in inflammatory and immune-mediated diseases such as canine osteoarthritis, chronic kidney disease, inflammatory bowel disease, and canine atopic dermatitis, where elevated CCL2 contributes to macrophage recruitment and sustained tissue inflammation. It is also implicated in infectious diseases and tumor biology, including canine lymphoma and osteosarcoma, where CCL2 can influence tumor-associated macrophage infiltration and tumor microenvironment remodeling. While CCL2-mediated immune cell trafficking supports pathogen defense and tissue repair, excessive or persistent expression can drive chronic inflammation and tissue damage. As a biomarker of monocyte/macrophage recruitment and inflammatory activation, canine CCL2 is widely used in studies of host–pathogen interactions, immune regulation, and disease progression. Because dogs serve as important spontaneous models for human inflammatory diseases and cancer, characterization of canine CCL2 supports translational research into chemokine signaling and development of targeted anti-inflammatory therapies.