Persistent spontaneous pneumomediastinum in a dog with pulmonary fibrosis

A 5‐year‐old, 5.8‐kg, neutered, male, mix‐breed dog was presented to the emergency service of a university hospital for assessment of respiratory distress. Thoracic radiographs identified a moderate pneumomediastinum, mild cervical subcutaneous emphysema and moderate bilateral diffuse bronchial and unstructured interstitial pulmonary patterns. The dog had a 6‐week long history of progressive respiratory signs before presentation, culminating in acute respiratory embarrassment in the absence of a precipitating event. Three sets of radiographs were performed before presentation, which demonstrated a persistent pneumomediastinum and progressively severe pulmonary infiltrates. The dog was humanely euthanased after 24 hours of hospitalised care, with a diagnosis of interstitial pulmonary fibrosis made at postmortem examination. Spontaneous pneumomediastinum is usually an acute condition, which resolves within a few weeks of diagnosis and does not recur. Persistent spontaneous pneumomediastinum has been described in people previously, and is a rare potential sequela to severe chronic pulmonary disease in dogs.