Actinobacillus pleuropneumoniae (APP)

• Respiratory distress is severe; there is thumping and occasionally open-mouth breathing with a blood-stained frothy nasal and oral discharge, fever, anorexia, and reluctance to move.

Diagnosis

• An explosive disease onset is suggestive.
• The pneumonia is usually bilateral.
• The characteristic lesion is a severe fibrinonecrotic and hemorrhagic pneumonia with accompanying fibrinous pleuritis.
• In acute cases, the lungs are dark and swollen and ooze bloody fluid from the cut surface.
• Hemorrhagic, even necrotic bullae (cavities) of various sizes may be present.
• The trachea may contain blood-stained froth. Bloody nasal/oral discharge is common.
• In chronic cases, the lesions are more organized and localized.