Uterine Microbiota Composition in Dairy Cows with Different Vaginal Discharge Scores: Suggesting Caviibacter as a Potential Pathogen in Mild Purulent Metritis

The uterine microbiota plays a crucial role in maintaining postpartum reproductive health in dairy cows, and its dysregulation is closely associated with uterine diseases. Vaginal discharge characteristics serve as important clinical indicators for assessing uterine status and guiding clinical decision-making. This study employed 16S rRNA gene sequencing to analyze uterine microbial diversity in cows with different discharge types. Results revealed significant microbial shifts associated with discharge severity. Notably, <i>Caviibacter</i> was highly enriched (up to 60.25%) in cows with mildly purulent discharge (<50%), suggesting its potential role in early-stage endometritis. In contrast, <i>Fusobacterium</i> and <i>Helcococcus</i> dominated when purulent discharge exceeded 50%, while <i>Bacteroides</i>, <i>Porphyromonas</i>, and <i>Peptostreptococcus</i> prevailed in cows with malodorous or discolored secretions, indicating severe inflammation. This study extends previous findings by uncovering stage-specific microbial transitions and proposing <i>Caviibacter</i> as a potential early biomarker of endometritis. These insights support early diagnosis and targeted interventions, contributing to improved reproductive management and sustainable dairy farming.