Fig. 2

Representative lung lesions and histological findings. a–c Heifer 2 showing lesions typical of fibrinous pneumonia (a). Histologically b, c there is central necrosis (asterisks) of airways and alveoli extending into interlobular septae (arrowheads), which show signs of beginning fibrosis. d, e Heifer 3 showing more progressed lesions of multifocal fibrinous pneumonia. d Histologically there is a thicker zone of inflammatory infiltrate (arrow) surrounding the central necrosis (asterisks) consisting of neutrophils, lymphocytes and macrophages and marked fibrosis affecting the interlobular septae surrounding the affected lobuli (arrowheads)