Small Animal Radiology and Ultrasound: A Diagnostic Atlas and Text

122 Small Animal Radiolo g y and Ultrasono graphy
Fig. 2-97 A 7-year-old female Springer Spaniel with a history of having swallowed a fish hook 2 days
earlier. On this lateral thoracic radiograph the fish hook is readily identified dorsal to the heart base.
There is a soft-tissue density surrounding the fish hook, and there is gas in the soft tissues dorsal to
this density (arrows). The radiographic findings indicate perforation of the esophagus by the fish
hook, with air within the mediastinum. Th e soft-tissue density that surrounds the fish hook may
represent bait that was on the fish hook at the time it was swallowed. Diagnosis: Fish hook in the thoracic
esophagus with penetration of the mucosa. The fish hook was removed by endoscopy.
Additional air was present in the mediastinum after removal of the fish hook. A contrast esophagram
was performed 3 days after foreign body removal and there was no evidence of leakage of contrast
material at the site of foreign body perforation. No complications were encountered.
the heart base, or cranial to the esophageal hiatus (Figs. 2-97 to 2-99). 251,252
Identification of these foreign objects on the ventrodorsal radiograph is often difficult
because of the overlying vertebral column. Esophageal dilation cranial to the foreign
object may provide a clue to its presence, but an esophageal contrast study may be necessary
to outline it. If an esophageal foreign body is identified or suspected, the thoracic
radiograph must be evaluated carefully for evidence of mediastinal or pleural fluid and
air, which indicate esophageal perforation. Aspiration pneumonia may be present if the
animal has been vomiting. The preferred method for performing an esophageal contrast
study in situations in which there is a likelihood or suspicion of esophageal perforation
should involve a water-soluble, nonionic contrast medium, because there is less potential
damage that could be inflicted on the lung should the patient aspirate the material. An
ionic water-soluble medium also could be used. 254 If the results of that study were negative,
a follow-up study with liquid barium should be considered to evaluate for occult
leaks. The contrast studies may not demonstrate contrast leakage despite noncontrast
radiographic evidence of esophageal perforation because of adhesions or fibrosis, which
may partially seal the perforation. 255 Esophagoscopy is the preferred method to delineate
an esophageal perforation.
E S O P H AG E A L F I S T U L A S
Tracheoesophageal and bronchoesophageal fistulas are rare in dogs and cats. 256-261
Mediastinal or pleural fluid or a localized pulmonary infiltrate may be observed in association
with these fistulas. However, there may be no survey radiographic findings suggestive
of a fistula despite notable clinical signs. The diagnosis requires demonstration of