Broncholithiasis associated with lower airway inflammation and subsequent pyothorax in a cat

CASE SUMMARY: A 12-year-old female spayed domestic shorthair cat presented with history of a long-term chronic cough that had worsened during the previous 2 months. Thoracic radiographs revealed numerous mineral opacities throughout the lung fields. Multiple bronchial plugs of pale yellow material were present on bronchoscopy, consistent with broncholithiasis. Bronchoalveolar lavage cytology revealed a mild neutrophilic inflammation and bacterial culture was negative. The cat was diagnosed with chronic inflammatory lower airway disease and broncholithiasis, suspected to be due to mineralisation of secretions in the bronchial lumen. The cat was treated for 6 years with oral prednisolone and responded well to treatment. Six years later, the cat developed severe respiratory distress and died. Post-mortem examination identified chronic multifocal broncholithiasis, pulmonary abscessation and pyothorax. RELEVANCE AND NOVEL INFORMATION: Broncholithiasis is a very rare condition in feline medicine; however, we are reporting a new case and it should be considered as a differential diagnosis for chronic coughing in cats, especially when other common causes have been ruled out and the radiographic findings are suggestive of it. We hypothesise that pathogenesis of the pulmonary abscessation and pyothorax in our patient was, at least partially, due to broncholithiasis. Pleural disease should be considered a complication of broncholithiasis.