Introduction

• Presence of air in pleural space.
• Cause: trauma, eg hit by car (HBC/RTA); spontaneous or secondary to other disease.
• Signs: respiratory distress.
• Diagnosis: radiography, thoracocentesis.
• Treatment: removal of free air from pleural space.
• Prognosis: always guarded initially as very volatile situation with sudden deterioration possible.

Pathogenesis

Etiology

• Trauma, especially road traffic accident.
• Penetrating thoracic wound.
• Spontaneous.
• Over enthusiastic ventilation during anesthesia.
• Pulmonary cysts.
• Lung abscess.
• Abscess due to tumor necrosis.
• Acute necrotizing pneumonia Lung: bacterial pneumonia.
• Iatrogenic.

Predisposing factors

• Large deep-chested dogs may be predisposed to spontaneous pneumothorax.

Pathophysiology

• Rib fracture, thoracic wall damage → damage to visceral pleura, thoracic wall, diaphragm → air enters pleural space → reduced lung expansion.
• Ruptured bleb or alveolar tissue in lung acts as one-way valve → air leaks into, and is trapped within, the pleural cavity → supra-atmospheric air pressure → lung pushed to side and chest wall bulge =tension pneumothorax.

• The mechanism behind spontaneous pneumothorax is the rupture of the bulla or bleb.
• It is not known why the bulla/bleb forms.

Timecourse

• Acute.

Diagnosis

Treatment

Outcomes