Pleuritis

()Map CARDIORESPIRATORY SYSTEM (Map) PLEURAL CAVITY AND MEMBRANES

Pleuritis

• Inflammation of the pleura
• Common in animals
• Inflammatory agents reach the pleura by:
  • Extension from pneumonia
    • Pleuropneumonia (fibrinous bronchopneumonia)- inflammation of mesothelial cells associated with parenchymal disease due to bacterial infection
  • Bloodstream
  • Trans-diaphragmatic lymphatics from peritoneal cavity
  • Penetration of the chest
  • From mediastinal abscessation
  • Penetration from oesophagus or abdominal viscus (commonly bovine traumatic recticulitis)
• Common acute forms:
  • Purulent
  • Fibrinous
    • Common sequele:
      • Organising fibrinous pleuritis in which the visceral pleura becomes enveloped in a restrictive fibrous blanket
      • Pleural adhesions, especially common in ruminants and pigs
• Granulomatous pleuritis may cause hypertrophic osteopathy

Pyothorax (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

Infectious causes of pleuritis

.	VIRAL	BACTERIAL	FUNGAL	PARASITIC
Dogs	.	Nocardia	.	.
.	.	Actinomyces and Bacteroides spp.	.	.
.	.	Tuberculosis	.	.
Cats	FIP	P. multocida and other Gram-negative organisms	.	.
Horses	Hendra virus	extension from nasopharyngeal flora	.	.
.	.	Streptococci	.	.
Cattle	.	Pneumonic pasteurellosis	.	.
.	.	Tuberculosis	.	.
.	.	Contagious bovine pleuropneumonia	.	.
Sheep	.	Enzootic pneumonia	.	.
Pigs	Swine influenza	Actinobacillus pleuropneumoniae	.	.
.	.	Pasteurellosis	.	.
.	.	Contagious porcine pleuropneumonia	.	.
.	.	Glasser's disease	.	.