• Also called thoracic empyema
  • Purulent effusion in the pleural space
  • Most significant in:
    • Horses
      • Usually secondary to pneumonia or lung abscesses
      • Streptococci are most commonly isolated
      • Usually yellow exudate
      • Often triggered by stress of travelling, competition or similar
    • Dogs
      • Often results from migrating grass awns
      • Actinomyces, Nocardia and Bacteroides spp. are the most frequently recovered organisms
      • Usually blood stained viscous or creamy exudate, often bilateral
      • Yellowish granules may be present within the exudate
      • Thickened pleura, sometimes fibrinous
    • Cats
      • Pathogenesis is unclear, possible due to bite wounds or penetrated oesophagus
      • P. multocida and other Gram-negative organisms are frequently recovered
      • Usually creamy yellow or greyish brown exudate, often bilateral