The torsion of a lung lobe at its hilus is a rare but life-threatening condition in dogs, commonly reported in large deep-chested breeds.
Torsion occurs when the lung lobe rotates around the bronchus and vascular supply and remains in that position. The patient may present in an acute, fulminant respiratory crisis; however, more subtle clinical signs have also been reported. Lung lobe torsion may be secondary to an underlying pathology or spontaneous and idiopathic.
Despite their small size, Pugs also appear to be predisposed to the condition, possibly due to bronchial cartilage dysplasia, resulting in bronchial hilus instability in brachychephalic breeds, making a lobar torsion more likely.
Lung-lobe torsion in dogs usually occurs secondary to accidental and surgical trauma, pleural effusion, chylothorax and pneumothorax. A predilection to torse the right middle lobe has been observed. This has been attributed to the narrow shape of the right middle lung lobe, its thin bronchovesicular pedicle, and its poor attachment to surrounding structures.
Clinically affected dogs present with dyspnea, tachypnea, lethargy, anorexia, pyrexia, cough and vomiting. Less commonly pale mucous membranes, cyanosis, pain on abdominal palpation and diarrhea are seen.
While survey radiographs, angiography, computed tomography, ultrasonography, and bronchoscopy have all been used in the diagnosis of lung-lobe torsion, the imaging technique most commonly used to make a diagnosis is survey thoracic radiographs.
Radiographs usually reveal variable degrees of lung lobe opacity, vesicular emphysema pattern and pleural effusion. There is usually enlargement, consolidation and emphysema of the affected lung lobe, with mediastinal shift to the contralateral side.
Ultrasonography may show hyperechoic consolidated lung lobe which are swollen with small irregular areas of cavitation.
Treatment usually requires lung lobectomy, which is often curative.
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