Page 796 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

Gastrointestinal system: 4.1 The upper gastrointestinal tr act 771

VetBooks.ir CONGENITAL AND DEVELOPMENTAL DISEASES OF THE EQUINE OESOPHAGUS

OESOPHAGEAL DUPLICATION CYSTS
INTRODUCTION
AND INTRAMURAL DUPLICATION CYSTS
Congenital diseases of the oesophagus are rare in
horses. Congenital stenosis, persistent right aor- Definition/overview
tic arch, oesophageal duplication cysts, intramural Oesophageal duplication cysts are congenitally rep-
duplication cysts and idiopathic megaoesophagus licated segments of the proximal oesophagus due to
have all been reported. the bifurcation of the embryonic oesophageal tube.
Intramural duplication cysts are evaginations within
CONGENITAL PERSISTENT the wall of the oesophagus lined by stratified squa-
RIGHT AORTIC ARCH mous epithelium, which are separated and isolated
from the main oesophagus.
Definition/overview
Congenital persistent right aortic arch is a rare Aetiology/pathophysiology
anomaly in which the 4 right aortic arch develops The lesions arise congenitally as elements of the
th
into the functional aorta instead of the normal left embryonic alimentary endoderm become separated
vessel. from the main alimentary tube. These lesions result
in external compression on the oesophageal lumen
Aetiology/pathophysiology causing effective obstruction.
A congenital condition where a fibrous remnant of
the ductus arteriosus acts to occlude the oesophagus Clinical presentation
between the aortic arch and the left pulmonary artery. A palpable, non-painful swelling may be present in
the cervical oesophagus, which increases as the cysts
Clinical presentation enlarge. They are usually not reducible. These swell-
Clinical signs are of oesophageal dysphagia and ings can cause impingement of the true oesophageal
obstruction, including salivation, and cervical lumen and may result in intermittent oesophageal
oesophageal distension. The oesophagus is usually dysphagia and signs of ‘choke’.
dilated cranial to the obstruction and with evidence
of diffuse oesophagitis. Differential diagnosis
Oesophageal obstruction, thyroid masses, cervical
Differential diagnosis abscessation, parotid salivary gland enlargement,
Oesophageal obstruction, 4 branchial arch defects, oesophageal diverticula.
th
megaoesophagus.
Diagnosis
Diagnosis Oesophagoscopy may reveal a lumen to be present in
The diagnosis is based on clinical signs of oesoph- the case of duplication cysts, which have been reported
ageal dysphagia. This can be confirmed by plain in young animals involving both the oesophagus and
and contrast radiographs showing dilatation of components of the oesophagus and trachea. Contrast
the oesophagus proximal to the ductus arteriosus. oesophagrams may show accumulation of contrast in
In addition, oesophagoscopy demonstrates a dilated the lumen of duplication cysts, which often commu-
proximal oesophagus with an apparent stricture just nicates with the oesophageal lumen. Cutaneous ultra-
cranial to the level of the heart. sonography is a useful technique for evaluating such
lesions non-invasively, being able to identify encapsu-
Management lated fluid-filled homoechoic structures. Ultrasound-
Successful surgical correction has been reported in guided aspiration may demonstrate squamous cells
one foal. Euthanasia may be more practical. supporting the diagnosis of an oesophageal cyst.