Hormone produced around calving that causes laxity of the collagen attachments of P3

• A. Relaxin
• B. Oxytocin
• C. Estrogen
• D. Progesterone

Answer: (A)

Relaxin mediates tissue remodeling and ligamentous laxity during late gestation. It is produced around calving and acts to soften collagen-rich attachments, including the ligaments that hold P3 in place. By increasing collagen turnover and reducing cross-linking, relaxin makes these connective tissues more pliable, which helps accommodate birth-related changes and can loosen the distal phalanx attachments. Other hormones like oxytocin drive uterine contractions, while estrogen and progesterone influence reproductive tract readiness and maintenance of pregnancy, but they do not specifically cause the laxity of P3 attachments seen around calving.