Progressive tension pneumomediastinum in an adult miniature schnauzer

A 1.5‐year‐old, female, spayed miniature schnauzer presented for a 1‐month history of progressive tachypnoea, exercise intolerance, weight loss and lethargy. Radiographs identified progressive pneumomediastinum and subcutaneous emphysema. Thoracic computed tomography confirmed the radiographic findings and did not show any underlying inciting aetiology. No oesophageal or tracheal lesions were identified during oesophagoscopy and tracheoscopy. No gross pathological lesions were visualised during the exploratory thoracotomy. The patient died 7 days following surgery. The final diagnosis was tension pneumomediastinum of uncertain aetiology. This case report highlights the imaging features of canine tension pneumomediastinum and the first documentation of the computed tomography imaging features.