Caprine Osteopontin (OPN) (also known as SPP1, Secreted Phosphoprotein 1, bone sialoprotein I, ETA-1, or early T-lymphocyte activation-1) is a multifunctional phosphorylated glycoprotein involved in immune regulation, cell adhesion, and tissue remodeling in goats (Capra hircus). Osteopontin interacts with integrins (such as αvβ3 and αvβ1) and CD44 receptors, activating signaling pathways that regulate cell migration, inflammatory responses, and extracellular matrix remodeling. In goats, OPN is produced by osteoblasts, macrophages, epithelial cells, and activated T lymphocytes, and plays important roles in bone metabolism, immune responses, and reproductive physiology. In caprine health, osteopontin is highly expressed in the uterine endometrium and placenta, where it contributes to embryo implantation, placental development, and maternal–fetal communication, making it important for successful pregnancy and reproductive efficiency. OPN also participates in inflammatory responses during mastitis and infectious diseases, where it helps regulate leukocyte recruitment and cytokine signaling in affected tissues. While osteopontin supports immune defense and tissue repair, excessive or prolonged expression may contribute to chronic inflammation or fibrotic tissue remodeling. As a regulator of immune cell migration, tissue remodeling, and reproductive signaling, caprine osteopontin is important for studies of host–pathogen interactions, mammary gland immunity, bone biology, and reproductive function relevant to goat health and small ruminant veterinary research.