Atypical Actinobacillosis in a Dairy Cow

Actinobacillosis is an infectious, chronic, generally non-fatal disease caused by Actinobacillus lignieresii. The etiologic agent is a part of the oral flora and causes pyogranulomatous lesions of the soft tissues. A 5-year old, approximately 500 kg cross-breed Holstein cow was presented for the treatment of a large, ulcerated and hemorrhagic mass at the left side of the neck in vicinity of the jugular furrow. Anamnesis indicated that the condition began three months previously as a small, walnut-size swelling that gradually enlarged over this period. After surgical resection of the mass, histological assessment revealed multiple pyogranulomatous foci-contained radiating eosinophilic clubs surrounded by many neutrophils, lymphocytes, plasma cells, macrophages and connective tissue. Clinical manifestations, bacteriological and pathological examinations of biopsy confirmed atypical actinobacillosis. In this case, the route of entry of organisms probably had been an abrasion or wound in the skin of the neck.