Page 488 - Small Animal Internal Medicine, 6th Edition

460 PART III Digestive System Disorders

referred to individuals with substantial experience in sometimes diagnosed fortuitously when thoracic radio-
their treatment. graphs are obtained for other reasons. Regurgitation,
VetBooks.ir Prognosis anorexia, and/or fetid breath may occur if the tumor is large
or causes esophageal dysfunction. If the esophagus is involved
Early identification and appropriate treatment of high-risk
function or tumor effects on other tissues.
animals (i.e., those with severe esophagitis or after foreign secondarily, clinical signs may result from esophageal dys-
object removal) help decrease the likelihood of stricture for-
mation. Resolving esophagitis decreases inflammation and Diagnosis
lessens fibrous connective tissue formation. Long esophageal Plain thoracic radiographs may reveal a soft tissue density in
strictures (i.e., > 3-5 cm), continuing esophagitis at the stric- the caudal lung fields. These tumors may be difficult to
ture site, and very chronic strictures seem to have a more discern radiographically from pulmonary or mediastinal
guarded prognosis. Most animals with benign esophageal lesions and usually require contrast esophagrams (Fig. 29.8)
strictures can be helped, but technical expertise is important. or esophagoscopy (Fig. 29.9) to diagnose. Endoscopy typi-
It is easy for a novice to perforate the esophagus or cause cally allows differentiation of intraluminal from extralumi-
excessive trauma and make the stricture quickly recur or nal masses causing esophageal stricture. Retroflexing the tip
perhaps even come back worse than it was. Long-term gas- of an endoscope while it is within the stomach is the best
trostomy tubes are rarely necessary. method of identifying LES leiomyomas and leiomyosarco-
mas near the gastric cardia.
ESOPHAGEAL NEOPLASMS
Treatment
Etiology Surgical resection is rarely curative (except for leiomyo-
Primary esophageal sarcomas in dogs are often due to Spiro- mas near the LES) because of the advanced nature of most
cerca lupi. Primary esophageal carcinomas are of unknown esophageal neoplasms when they are diagnosed. However,
etiology. Leiomyomas and leiomyosarcomas are often found resection may be palliative. Photodynamic therapy may be
at the lower esophageal sphincter in older dogs. Thyroid beneficial in dogs and cats with small superficial esopha-
carcinomas and pulmonary alveolar carcinomas may invade geal neoplasms. Surgery near the LES should be done
the esophagus in dogs. Squamous cell carcinomas are the only by an experienced surgeon; it is easy for an inexpe-
most common esophageal neoplasm in cats. rienced surgeon to cause more disease than was present
before.
Clinical Features
Dogs and cats with primary esophageal tumors may be Prognosis
asymptomatic until the tumor is advanced. These animals are The prognosis is usually poor (except for leiomyomas).

A B

FIG 29.8
(A) Lateral thoracic radiograph of a dog with a previously unsuspected mass (arrows) not
obviously associated with the esophagus. (B) Contrast esophagram in the same dog
demonstrates that the esophagus is dilated (large arrows) and that there are
intraesophageal filling defects (small arrows) in this dilated area. This dog had a primary
esophageal carcinoma. (A, From Allen D, ed.: Small animal medicine, Philadelphia,
1991, JB Lippincott.)