Abstract: During hot summers,heat stress significantly increases the incidence of postpartum uterine infections （e.g.,metritis,endometritis and pyometra）in dairy cows. Key contributing factors include pathogen proliferation in high temperatures,delayed uterine involution,immune suppression and negative energy balance.This paper systematically analyzed the pathogenesis,diagnostic methods,and preventive measures for postpartum metritis,aiming to reduce its incidence,improve reproductive performance,and minimize economic losses.The study provided theoretical and practical guidance for managing reproductive health in dairy herds during summer.

Key words: dairy cows, metritis, heat stress, uterine involution