Abstract
Reports of the identification and successful clinical management of mediastinal masses in adult cattle are uncommon. A two‐year‐old Holstein heifer presented with tachycardia, muffled heart sounds and oedema, similar to a cow with traumatic reticulopericarditis. Following several diagnostics including thoracic ultrasonographic examination, a cranial mediastinal mass was identified. An empirical antibiotic treatment was attempted without resolution of clinical signs. Successful treatment required an ultrasound‐guided drainage of the mass and antibiotic therapy based on culture and sensitivity. This case is interesting because each of the likely differentials that could explain the physical exam findings on initial presentation is associated with a poor prognosis for recovery. To the authors’ knowledge, this is the first report of pericardial effusion and cardiac tamponade secondary to mediastinal obstruction of pericardial drainage in any domestic species. The report supports the use of an uncomplicated, systematic approach to cases of thoracic disease in adult cattle.