Interstitial Pneumonia

Interstitial pneumonia (Image sourced from Bristol Biomed Image Archive with permission)

• Lung inflammation that occurs primarily in alveolar walls rather than in alveolar spaces
• Can be widely distributed but is often most severe in caudal lung lobes
• Diffuse or patchy damage to alveolar septa, may be acute or chronic
• Lesions in most cases result from blood-borne insult and are more likely to involve the dorsocaudal regions, although the damage is often diffuse
• No concentrated inflammatory response in the airway, only secondary to damage of alveolar walls
• As part of systemic infection
  • Canine distemper (in alveolar macrophages as inclusions)
  • Salmonellosis
  • Toxoplasmosis (in alveolar wall)

• Acute interstitial pneumonia is characterised by exudation into the alveolar lumen and in cattle is associated with interstitial emphysema

Examples: