On a radiograph of a cat thorax with an elevated trachea and caudally displaced heart, what's the cause?

• A. Pneumothorax
• B. Pulmonary edema
• C. Mediastinal mass
• D. Pericardial effusion

Answer: (C)

A mediastinal mass is the pattern most consistent with this radiographic finding. A mass occupying the mediastinum, especially in the cranial part where the trachea sits, can push the trachea upward and shove the heart caudally. In cats, thymoma is a classic mediastinal mass that can produce this exact appearance by creating space-occupying pressure within the mediastinum.

Pneumothorax would typically show a loss of normal lung markings with air in the pleural space and a mediastinal shift that isn’t specifically tied to elevating the trachea or pushing the heart caudally. Pulmonary edema usually presents with diffuse interstitial or alveolar markings and sometimes an enlarged cardiac silhouette, not a discrete mediastinal mass effect. Pericardial effusion tends to give a more globular, rounded cardiac silhouette with a different set of shifts, rather than the tracheal elevation and caudal cardiac displacement seen with a mediastinal mass.