Grass awns are foreign bodies that commonly embed in the skin, feet, eyes, nose, lumbar area, thoracic cavity, and ears of dogs and cats. Because grass awns have sharp points with backward pointing barbs, the skin is easily penetrated and retrograde movement is limited. Recovery is good if the awn can be identified and removed. This study describes the clinical, radiographic, and computed tomography (CT) findings in 35 dogs and 5 cats with migrating intrathoracic grass awns. The most common signs included cough, fever, gagging, retching, respiratory difficulty, lethargy, and anorexia. Duration of clinical signs varied from 2 days to 1 year. An inflammatory leukogram with a left shift was the most common finding on complete blood count. Thirty-eight animals had thoracic radiographs, and common clinical findings included a focal pulmonary interstitial to alveolar pattern most commonly associated with the caudal or accessory lung lobes. Pneumothorax, pleural effusion, and pleural thickening were also common. Pulmonary opacities correlated with areas of pneumonia and foreign body reactions. Fourteen animals had CT examinations, and findings included focal interstitial to alveolar pulmonary opacities, pleural thickening, mildly enlarged lymph nodes, pneumothorax, and pleural effusion. In 4 cases, the foreign body could be seen. Grass awns were removed via endoscopy in 23 cases and via surgery in 13 cases.

COMMENTARY:
The take-home message from this article is that migrating grass awns are common in young dogs, especially Labrador retrievers and English pointers. Dogs presenting with a cough, fever, and inflammatory leukogram with a left shift should raise a high degree of suspicion. Diagnosis can be made via thoracic radiographs; interstitial to alveolar pulmonary opacities, pleural effusion or thickening, and pneumothorax are highly compatible findings. CT can be helpful to visualize the lesion, which may facilitate removal via endoscopy. Compared with radiographs, CT finds more sites of abnormalities, correctly determines the site, and traces the path of the foreign body more accurately than do radiographs.

Radiographic, computed tomographic, and ultrasonographic findings with migrating intrathoracic grass awns in dogs and cats. Schultz RM, Zwingenberger A. VET RADIOL ULTRASOUND 49:249-255, 2008.