Postpartum Uterine Diseases in Dairy Cattle: Integrating Microbiology, Immunology, and Reproductive Physiology.

Postpartum uterine diseases are among the most prevalent and economically important reproductive disorders affecting dairy cattle worldwide. These conditions, including metritis, clinical and subclinical endometritis, and pyometra, develop during the postpartum transition period when physiological, metabolic, endocrine, and immunological adaptations increase susceptibility to microbial invasion and persistent uterine inflammation. Although bacterial contamination of the postpartum uterus is nearly universal, healthy cows generally restore uterine homeostasis through coordinated immune responses, microbial regulation, and effective uterine involution. Failure of these defense mechanisms results in microbial dysbiosis, impaired endometrial repair, reduced fertility, and substantial economic loss. Major pathogens associated with postpartum uterine disease include Escherichia coli, Trueperella pyogenes, Fusobacterium necrophorum, Prevotella spp., and other anaerobic bacteria that interact synergistically to promote inflammation, tissue damage, and reproductive dysfunction. Advances in next-generation sequencing, metagenomics, and metatranscriptomics have transformed understanding of the postpartum uterine microbiota and host-microbe interactions involved in disease pathogenesis. This review synthesizes current evidence regarding uterine physiology, microbial ecology, immune regulation, virulence mechanisms, dysbiosis, diagnostic approaches, and emerging omics-based technologies relevant to postpartum uterine disease in dairy cattle. Particular emphasis is placed on the ecological and physiological interactions linking microbial succession, endocrine recovery, metabolic stress, and immune competence during the postpartum period. The review further discusses translational opportunities for precision diagnostics, microbiome-informed interventions, antimicrobial stewardship, and integrated herd management strategies to improve reproductive efficiency, animal welfare, and dairy herd sustainability.