During the post-mortem inspection of a casualty slaughter cow (Japanese Black, 56-month-old) at a slaughterhouse in Kagoshima Prefecture, a multifocal mass, approximately 1-4 cm in diameter, was found mainly in the soft tissues of the abdominal cavity. The presence of intra-abdominal disseminated tumors or multiple infectious foci was suspected. Histologically, the mass showed pyogenic granuloma with asteroid bodies. Gram-negative rods inside the asteroid bodies reacted positively to immunohistochemistry with rabbit anti-Actinobacillus lignieresii serum. Gram-negative rods isolated from the mass were identified as A. lignieresii by biochemical characterization and partial sequencing of the 16S rRNA gene and rpoB gene. Based on these findings, the case was finally diagnosed as intra-abdominal actinobacillosis.