Introduction

• Rare finding in companion animal medicine.
• Cause: inflammation of the pleura.
• Signs: dyspnea, tachypnea, pyrexia, depression.
• Diagnosis: radiography, thoracocentesis and cytology.
• Prognosis: good to guarded depending on etiology.

Pathogenesis

Etiology

• Tuberculosis Pulmonary tuberculosis.
• Actinomycosis.
• Nocardiosis.
• Trauma or infection due to bite wound or pleural foreign body.
• Mesothelioma Mesothelioma.
• Tumors within visceral or parietal pleura (physical abrasion → exudation).
• Hematogenous spread of infection from other sites.
• Auto-immune disease.
• Irradiation (thoracic radiotherapy).
• Canine infectious hepatitis Liver: chronic hepatitis.
• Leptospirosis Leptospirosis.
• Idiopathic.

• Iatrogenic:
  • Esophageal rupture after endoscopic procedure.
  • Contamination from thoracocentesis.
• Associated with pneumonia Lung: bacterial pneumonia.
• Uremia Uremia.
• Mediastinitis Trachea: foreign body.
• Pyometra Pyometra.

Pathophysiology

• Initially pleural inflammation results in a non-effusive pleuritis.
• Pain is generated as the visceral and perietal pleural layers rub against one another during the respiratory cycle.
• Rapidly progresses to a serous pleuritis.
• The pleura become thickened and the production of a fluid effusion helps the surfaces to glide more easily.
• Bacterial pleuritis may progress to effusive pyothorax.
• Following inflammation the pleura may become scarred and fibrosed.
• The fibrosis makes the pleura rigid and this results in constrictive pleuritis in which the lungs are unable to expand normally.
• If the pleura are drained in this situation, rupture of the visceral pleura may occur and a pneumothorax may develop.

Diagnosis

Treatment