Lung lobe torsion in the dog: radiographic signs
3-year-old Pug with progressive dyspnoea and lethargy for 3 days. The radiograph shows pleural effusion, consolidation of the left cranial lobe with a pattern of small gas bubbles, and a lobar bronchus that ends abruptly.
What is the most likely diagnosis?
chevron_right Show answer and explanation
A. Aspiration pneumonia of the left cranial lobe
It is common in brachycephalic dogs, but it produces air bronchograms with normally coursing bronchi, not a truncated bronchus with vesicular gas and pleural effusion.
B. Primary lung neoplasia
Primary lung tumours occur in older dogs and form a mass, usually without the vesicular gas pattern or truncated bronchus.
C. Lung lobe torsion
Correct. A consolidated lobe with vesicular gas, an abruptly ending or abnormally positioned bronchus and pleural effusion are the classic signs. In Pugs the left cranial lobe is typically affected; in large deep-chested breeds, the right middle lobe.
D. Diaphragmatic hernia with the stomach in the thorax
A herniated viscus is continuous with the abdomen and accompanied by loss of the diaphragmatic outline, not by a truncated lobar bronchus.
lightbulb Key takeaway
Pleural effusion can hide the twisted lobe: repeat radiographs after drainage or use CT, which shows the occluded bronchus and an enlarged, non-enhancing lobe. Treatment is lobectomy, without untwisting the pedicle before ligation. Pleural effusion (including chylous effusion) can also predispose to torsion.
Test yourself with 10 random questions
Diagnostic imaging · 200 questions, a different test every time
Related questions
Updated: October 31, 2026 · Educational content for veterinary professionals. It does not replace current clinical guidelines or the judgement of the attending veterinarian.