Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

Chapter Two The Thorax 117
A
Fig. 2-92 A 3-month-old female
Dachshund with a history of regurgitation
after the owner started feeding
the dog solid food. The
regurgitation occurred shortly after
ingestion. A, Ventrodorsal and lateral
thoracic radiographs were obtained.
The cranial mediastinum is widened.
There is an air-filled density in the
cranial mediastinum (solid arrows).
This is indicative of a dilated cranial
thoracic esophagus. There is a localized
alveolar pattern infiltrate in the
right middle lung lobe (open
arrows). This is due to aspiration
pneumonia. B, An esophagram was
performed. The esophageal dilation
cranial to the cardiac silhouette is
identified. The esophagus caudal to
the cardiac silhouette is normal. The
area of stenosis is evident on the lateral
and ventrodorsal radiographs
(arrows). Diagnosis: Vascular ring
anomaly. Persistent right aortic arch.
B
may be observed at the thoracic inlet, especially in normal brachycephalic dogs. A small
amount of air may be seen within the esophagus at this point on a noncontrast study.
However, a contrast esophagram usually is required to demonstrate this local dilation. It
lacks clinical significance.
Esophageal strictures may occur at any site, with the more common sites being at or
just anterior to the thoracic inlet, over the base of the heart, or near the gastroesophageal
junction. The esophagus proximal to the lesion may be dilated. Diagnosis of a stricture
requires a contrast esophagram (Fig. 2-94). It may be necessary to mix the barium with
food, because liquid barium may pass through without interference if the stricture is mild.
Treatment may be performed by balloon-catheter dilation, with positioning of the balloon
under fluoroscopic guidance. 236,237
Many patients swallow air during radiography, and a localized air accumulation within
the esophagus must be identified on at least two radiographs and must be consistent in
size, shape, and location to be considered significant. Local accumulations of food or bony
material are more significant. Unless the density can be identified as a foreign object, an
esophageal contrast study is needed to evaluate the cause of the food accumulation. With
time, a local esophageal dilation may become generalized.