Spontaneous pneumothorax in the cat: look for the lung disease
8-year-old Siamese cat diagnosed with asthma 3 years ago, with poor treatment compliance. Acute dyspnoea without trauma: rapid, shallow breathing and reduced dorsal lung sounds. Bilateral thoracocentesis removes 180 mL of air and the cat improves.
Which statement is correct?
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A. As in dogs, subpleural bullae are likely: thoracotomy is indicated
In dogs, spontaneous pneumothorax is usually primary from bullae and responds poorly to conservative treatment; in cats the pattern is different, and surgery is reserved for persistent leaks or focal lesions.
B. It is a primary idiopathic pneumothorax: no further work-up is needed unless it recurs
Primary pneumothorax is rare in cats; not investigating the cause leaves the underlying disease untreated and favours recurrence.
C. Asthma does not cause pneumothorax: look for an unwitnessed trauma
Air trapping and hyperinflation in asthma can rupture alveoli; bronchial disease is one of the most commonly reported causes of spontaneous pneumothorax in cats.
D. It is usually secondary to lung disease, often bronchial; investigate and treat the cause
Correct. In cats, spontaneous pneumothorax is usually secondary: feline bronchial disease, neoplasia, lungworm, heartworm or pneumonia. Many are controlled with thoracocentesis or a drain plus treatment of the cause.
lightbulb Key takeaway
An asthma crisis that does not respond to a bronchodilator may be a pneumothorax: look for absent lung sliding on ultrasound. Once the lung has re-expanded, complete the work-up: radiographs or CT, bronchoalveolar lavage, Baermann and heartworm tests.
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Updated: November 1, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.