Lung Lobe Blowout: CT Highlights Key Signs of Lobar Emphysema in Dogs and Cats

Imaging findings in 14 dogs and 3 cats with lobar emphysema

Harry Warwick, James Guillem, Daniel Batchelor, Tobias Schwarz, Tiziana Liuti, Sally Griffin, Erin Keenihan, Marie-Laure Theron, Swan Specchi, Giuseppe Lacava, Jeremy Mortier

Background
Lobar emphysema in dogs and cats is a rare condition caused by bronchial collapse during expiration, leading to air trapping and hyperinflation of affected lung lobes. While congenital causes such as bronchial cartilage defects are common in young animals, acquired causes like neoplasia or diaphragmatic hernia may contribute in older animals. The study aimed to characterize the clinical and imaging features of lobar emphysema in a multicenter population of companion animals.

Methods
Seventeen animals (14 dogs, 3 cats) diagnosed with lobar emphysema via thoracic radiography and/or computed tomography (CT) between 2008 and 2018 were retrospectively reviewed. Imaging findings were analyzed by board-certified radiologists, and histopathology was reviewed when available. Affected lobes, presence of bronchial collapse, vascular changes, and thoracic structural alterations were assessed alongside patient demographics and clinical presentation.

Results
Most cases (82%) were suspected to be congenital, with 65% of animals under 3 years old. The right middle lung lobe was the most frequently affected (71%). CT proved superior to radiography in identifying the affected lobe, collapsed bronchi, and concurrent structural changes. Common imaging findings included lobe hyperinflation, atelectasis of adjacent lobes, mediastinal shift, thoracic wall deformation, and diaphragmatic flattening. Small pulmonary vessels in emphysematous lobes and bronchial collapse were seen in 93% of CT cases. Surgical treatment (primarily lobectomy) was performed in 10 animals, with 80% survival to discharge. Histopathology confirmed congenital lobar emphysema (CLE) in 8 animals, with bronchial cartilage hypoplasia identified in half of these.

Limitations
The retrospective nature and variability in imaging protocols limited uniformity. Not all cases had complete histopathologic confirmation, and only a subset underwent both CT and radiography. The use of sedation and positive pressure ventilation during imaging may have influenced pulmonary findings.

Conclusions
Lobar emphysema, particularly involving the right middle lung lobe, should be considered in young dogs and cats with dyspnea or coughing. While radiographs can suggest the diagnosis, CT is the preferred modality for accurate lobe identification, assessing bronchial collapse, and planning surgery. In older animals, secondary causes such as neoplasia should be ruled out. Early CT evaluation supports timely diagnosis and effective surgical intervention with good short-term outcomes.

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