The Presence Effect of Trueperella pyogenes in the Uterus at 2 Weeks Postpartum on the Progression of Cytological Endometritis and Ultrasonographic Findings in Dairy Cows.

We investigated the degree of endometrial inflammation and the fluid in the uterus (FIU) scores in Holstein cows with or without intrauterine Trueperella pyogenes infection. Scoring of FIU by transrectal ultrasonography, percentage of polymorphonuclear neutrophils (PMN%) measurement, and bacterial species identification in endometrial samples were performed at 2, 5, and 7 weeks postpartum. Threshold for cytological endometritis based on PMN% was set at ≥ 6% and ≥ 4% at 5 and 7 weeks postpartum, respectively. Cows were categorized into the T. pyogenes-positive (Tp group, n = 25) and T. pyogenes-negative groups (non-Tp group, n = 24) based on the presence of intrauterine T. pyogenes infection at 2 weeks postpartum. The prevalence of cytological endometritis at 5 and 7 weeks postpartum was significantly (p < 0.01) higher in the Tp group than in the non-Tp group (84.0% vs. 16.7% at 5, and 68.0% vs. 9.1% at 7 weeks postpartum). The Tp group exhibited significantly (p < 0.05) higher FIU scores and PMN% at 5 and 7 weeks postpartum than the non-Tp group. Intrauterine T. pyogenes infection at 2 weeks postpartum might be associated with high PMN%, cytological endometritis prevalence, and FIU scores during the postpartum period.