Radiographic, computed tomographic, and ultrasonographic findings with migrating intrathoracic grass awns in dogs and cats

The purpose of this study was to describe the clinical, radiographic, and computed tomographic findings in dogs and cats with migrating intrathoracic grass awns. Thirty-five dogs and five cats with visual confirmation of a grass awn following surgery, endoscopy or necropsy, and histology were assessed. The medical records and all diagnostic imaging studies were reviewed retrospectively. Labrador Retrievers or English Pointers < 5 years of age, with a history of coughing and hyperthermia, were the most common presentations. Seventeen animals had an inflammatory leukogram of which 14 had a left shift or toxic neutrophils. Radiographs were performed in 38 animals and computed tomography (CT) in 14. Thoracic radiographs were characterized by focal pulmonary interstitial to alveolar opacities (n=26) that occurred most commonly in the caudal (n=19) or accessory lobes (n=8). Additional findings included pneumothorax (n=9), pleural effusion (n=8), and pleural thickening (n=7). Pulmonary opacities identified on radiographs correlated to areas of pneumonia and foreign body location. CT findings included focal interstitial to alveolar pulmonary opacities (n=12) most commonly in the right caudal lung lobe (n=9), pleural thickening (n=11), mildly enlarged intrathoracic lymph nodes (n=10), soft tissue tracking (n=7) with enhancing margins (n=4), pneumothorax (n=6), pleural effusion (n=4), and foreign body visualization (n=4). Histologic diagnoses included pulmonary and mediastinal granulomas or abscesses, bronchopneumonia, and pleuritis. Migrating intrathoracic grass awns should be considered as a differential diagnosis in coughing, febrile animals with focal interstitial to alveolar pulmonary opacities, pleural effusion, pleural thickening, and/or pneumothorax on radiographs or CT.