Endometritis is the most common reproductive infertility problem in dairy animals. This study aimed to investigate the relation between the histopathological characterization of endometritis and ovarian steroid hormones in both uterine tissue and follicular fluids (FF) in addition to the proinflammatory cytokines and myeloperoxidase (MPO). Uteri collected from slaughter houses were subjected to hematoxylin and eosin (H&E) routine staining and Antisyndecan-1 immunohistochemistry aids to classify the type of endometritis. Bacteria in the apex of the examined uterine horns were isolated and identified. FF and uterine tissues homogenate were used to assay E2, progesterone (P4), tumor necrosis factor α (TNFα) and MPO. Results showed that sample-species type (cow uteri, buffalo uteri, cow FF, and Buffalo FF fluids) influenced (P<0.0001) MPO, E2, and P4. Uterine (Ut) pathology (acute suppurative, acute lymphocytic, chronic suppurative, chronic metritis, and normal); the isolated bacteria; Ut Pathology × Sample-Species; Ut Pathology × bacteria; and Bacteria ×Sample-Species influenced (P<0.0001) TNFα, MPO, E2, and P4. Ut Pathology × bacteria × Sample-Species affected TNFα, MPO, and P4. In conclusions, Immunohistochemistry is a reliable method to confirm the chronicity of endometritis. Both TNFα and MPO would be reliable markers for determining endometritis. Endometritis likely altered the FF proinflammatory markers and the steroid hormones and sequentially the future fertility. Buffaloes seem sensitive to uterine pathology caused by bacteria.