| Clinical Cases
| Case Answer/Discussion
There is relatively uniform widening of the cranial and
caudal mediastinum on the dorsoventral view. On the lateral view,
the heart and ventral diaphragm are poorly visualized due to silhouetting
with soft tissue opacity material within the mediastinum. A pleural
fissure line is present overlying the cardiac silhouette on the
lateral view, and the caudal lung lobes are slightly separated
from the thoracic wall by soft tissue opacity material on the
DV view. No other abnormalities are detected. Given the history,
the most likely differential is mediastinal hemorrhage and mild
bilateral pleural hemorrhage secondary to rodenticide toxicity.
The normal mediastinum should be no more than twice the
width of the spine on the DV view. The relative uniformity of
the widening in this case makes the presence of mediastinal fluid
more likely than the presence of a mass. Without the history of
possible rodenticide toxicity, another differential diagnosis
would be the presence of pus within the mediastinum, possibly
secondary to a perforating esophageal foreign body.
radiographic findings in dogs with anticoagulant rodenticide toxicity
have been described. Findings include increased mediastinal soft
tissue opacity with or without tracheal narrowing, variable amounts
of pleural effusion, and patchy pulmonary infiltrates. (1) The
patient in this case had mediastinal fluid without tracheal narrowing
and mild pleural effusion, but no pulmonary infiltrates. Remember
that the mediastinum extends from the spine to the sternum, so
it is superimposed on the lung fields on the lateral view. This
can give the false impression of pulmonary changes. Luckily, evaluation
of the lung fields is still possible on the DV view.
Berry CR, Gallaway A, Thrall DE, Carlisle C. Thoracic radiographic
features of anticoagulant rodenticide toxicity in 14 dogs. Vet
Radiol Ultrasound 34(6):391-396, 1993.