Granulomatous Omentitis in Multiple Sheep Associated With Trueperella pyogenes and Corynebacterium pseudotuberculosis: A Case Series

Background Granulomatous omentitis is a relatively rare but significant inflammatory condition in sheep, often associated with persistent bacterial infections. Dual infection with Trueperella pyogenes and Corynebacterium pseudotuberculosis is rare, and detailed studies elucidating their combined role in disease pathogenesis remain limited. Objectives This study investigated the occurrence, pathological features, and microbial aetiology of granulomatous omentitis in sheep from a slaughterhouse in Rey, Iran, with a focus on molecular detection of T. pyogenes and C. pseudotuberculosis . Methods A total of 6000 sheep were inspected post‐mortem between 2022 and 2024. Gross examination identified omental nodules, from which tissue samples were collected. Histopathological analysis, PCR amplification of species‐specific genes, and correlation of molecular findings with histology were performed. Results Nodular omental lesions were present in 0.5% of examined sheep. Histopathology demonstrated granulomatous inflammation characterized by epithelioid macrophages, multinucleated giant cells, and central caseous necrosis. PCR confirmed co‐infection in all cases (25/25). The pathological and molecular evidence suggests a synergistic role of both pathogens in chronic omental inflammation. Conclusions These findings highlight the importance of considering co‐infections in granulomatous omentitis and suggest that future studies should focus on the pathogenesis of dual infections and the development of effective control measures, such as targeted vaccination strategies.