Introduction

• Uncommon, usually incidental finding at post-mortem examination, rarely of clinical significance.
• Cause: chronic respiratory diseases, eg chronic bronchitis, rarely congenital.
• Signs: expiratory respiratory difficulty, inspiratory crackles on auscultation, wheezing, cyanosis.
• Diagnosis: radiography.
• Treatment: treat underlying disease, lobectomy if congenital and less than 3 lobes affected.
• Prognosis: rarely causes clinical problems, congenital form may result in death from pneumothorax.

Pathogenesis

Etiology

• Congenital.
• Chronic respiratory diseases.

Specific

• Respiratory distress (all causes).

• Damage to alveoli walls.

Pathophysiology

• Increased negative intrapleural pressure associated with partial respiratory tract obstruction → tearing of bronchoalveolar walls.
• Emphysema is caused by the coalescence of the alveoli into large cavernous spaces.
• During inspiration there is overinflation of the emphysematous lung areas with consequent air trapping during expiration resulting in expiratory difficulty.
• Large cavities (bullae) can be identified radiographically.
• In acquired emphysema these changes are secondary to chronic respiratory diseases such as chronic bronchitis Chronic bronchitis or bronchopneumonia (the latter 2 conditions may also be the consequence of emphysema).
• Congenital lobar and bullous forms are described in young dogs, but are rare conditions.

Timecourse

• Months to years.
• Pneumothorax Pneumothorax may develop within minutes once bullae rupture.

Diagnosis

Treatment

Outcomes