Equine Platelet-Derived Growth Factor-BB (PDGF-BB) is a homodimeric growth factor composed of two PDGF-B chains that plays a key role in cell proliferation, migration, angiogenesis, and tissue repair in horses (Equus caballus). PDGF-BB signals primarily through platelet-derived growth factor receptor-β (PDGFR-β) and PDGFR-α/β receptor complexes, activating downstream signaling pathways including PI3K/AKT, MAPK, and STAT, which regulate fibroblast activation, smooth muscle cell proliferation, and extracellular matrix production. In horses, PDGF-BB is produced by platelets, macrophages, endothelial cells, and fibroblasts and is released during tissue injury, inflammation, and wound healing. It plays particularly important roles in musculoskeletal tissue repair, including healing of tendons, ligaments, cartilage, and bone, which are critical tissues in equine athletic performance. PDGF-BB also contributes to dermal wound healing and vascular remodeling, promoting fibroblast migration and angiogenesis at sites of injury. Because of its regenerative properties, PDGF-BB is widely studied in equine regenerative medicine, including platelet-rich plasma (PRP) therapies used to treat tendon and ligament injuries. As a regulator of cellular growth, angiogenesis, and tissue remodeling, equine PDGF-BB is important for studies of wound healing, musculoskeletal injury repair, and regenerative therapies relevant to equine health and performance.