Lobar Pneumonia

• May be considred as a variation of bronchopneumonia and can be described as an aggressive fulminating bronchopneumonia
• Entire lung lobes or major parts of lung lobes are uniformly consolidated
• The consolidation is not obviously oriented around terminal bronchioles
• Although it can and often is caused by infectious agents that reach alveoli by descending through terminal bronchioles, the rapid spread of the agent throughout the lung parenchyma obliterates any bronchiolar orientation
• A good example is lobar pneumonia observed following Pasteurella (Mannheimia) haemolytica infection in cattle
• These lesions are often extensions of bronchopneumonia therefore again tend to have a cranioventral distribution
• Seen in aspiration of foreign fluids or gastric contents
• In dogs and cats, this is the common appearance of pneumonia because of the lack of complete lobulation and septation
• Gross pathology:
  • Affected area dark red and there may be pleural exudation
  • Haemorrhages and perhaps tissue necrosis
• Micro pathology:
  • Necrotic foci involving all tissue within affected area, with a surrounding rim of leukocytes (often undergoing necrosis), inside of which bacterial colonies may be seen
  • Gut contents in aspiration
• Sequel: commonly death, in survival fibrosis of the affected areas, pleuritis