Fibrosing pleuritis in canine chylothorax: radiographs
7-year-old dog with chronic recurrent chylothorax. After needle thoracocentesis removing a large volume of chyle, left lateral and ventrodorsal radiographs are repeated:
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Despite drainage, the lung lobes remain retracted with rounded margins and the pleura looks thickened. What does this finding indicate?
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A. Lung lobe torsion after drainage
Torsion affects a single lobe, which looks consolidated, sometimes with vesicular gas and an abnormally positioned bronchus. It does not explain all lobes being retracted and rounded.
B. Fibrosing pleuritis preventing re-expansion
Correct. Chronic exposure to chyle thickens the visceral pleura, which acts like a rind: the lobes cannot re-expand and keep rounded margins even without fluid. The gas left between lung and wall (pneumothorax after the tap) makes it obvious.
C. Transient atelectasis that will resolve in hours
Compressive atelectasis corrects once the fluid is drained and the lung margins regain their sharp shape. Persistently rounded margins indicate restriction.
D. Re-expansion oedema after rapid drainage
Re-expansion oedema increases the opacity of lung that has re-expanded. It does not produce retracted lobes with rounded margins.
lightbulb Key takeaway
In chronic chylothorax or pyothorax, lobes that fail to re-expand and keep rounded margins after drainage indicate fibrosing pleuritis. It worsens the prognosis, predisposes to persistent pneumothorax after thoracocentesis and may need decortication; controlling the effusion early reduces the risk.
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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.