Page 797 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

772 CHAPTER 4

VetBooks.ir Management Clinical presentation
Observation while grazing can reveal palpable dila-
Successful treatment of the cysts has been performed
by marsupialisation of the cyst. Attempted removal
of the cyst in toto can be complicated by dehiscence tation of the oesophagus on the left-hand side of the
neck, which may be reducible when the head is raised
of the oesophageal lumen and mediastinitis. (Fig. 4.99). Such impaction is more obvious when
solid food is being ingested and may not be obvi-
MEGAOESOPHAGUS ous with liquid food. Since the obstruction is incom-
plete, such animals may learn to compensate and to
Definition/overview maintain body condition. Aspiration pneumonia is a
Persistent dilatation of the oesophagus, resulting in possible secondary complication.
failure of peristalsis and accumulation of ingesta in
the oesophagus. Differential diagnosis
Oesophageal obstruction, oesophageal diverticula.
Aetiology/pathophysiology
Primary megaoesophagus is a very rare occurrence Diagnosis
in horses and is a consequence of motor dysfunc- Such cases may present with obstruction at the cau-
tion of the oesophageal musculature. Congenital dal oesophageal sphincter with damming of ingesta
oesophageal dilatation syndrome involving neural cranially, which may be visible on plain and contrast
and muscular components has also been described. radiographs.
Secondary megaoesophagus can be associated with
other conditions such as equine grass sickness, bot- Management
ulism, toxicity with lead, thallium or anticholines- Dietary management will help avoid complete oesoph-
terase and following sedation with acepromazine ageal obstruction and aspiration of food. Transient
and detomidine. Neurological dysfunction associ- secondary cases can gradually improve after conser-
ated with acquired diseases such as equine proto- vative treatment. Permanent megaoesophagus with
zoal meningitis (EPM) and equine herpesvirus-1 persistent dysphagia carries a guarded prognosis.
(EHV-1) can also result in temporary megaoesopha-
gus. A transient megaoesophagus can be observed GASTRO-OESOPHAGEAL
after persistent oesophageal obstruction or indwell- REFLUX SYNDROME
ing NG tube placement.
Definition/overview
A condition in which gastric contents are refluxed in
4.99 to the caudal oesophagus.

Aetiology/pathophysiology
Reflux oesophagitis is the consequence of repeated
episodes of gastric fluid regurgitation into the dis-
tal oesophagus. The gastric acid results in chemical
injury to the mucosa and eventually mucosal slough-
ing and ulceration can occur if the gastric fluids are
not cleared. Reflux oesophagitis may occur in com-
bination with gastric ulcer disease, motility disor-
ders including intestinal ileus or distal oesophageal
sphincter dysfunction. It is most common in wean-
lings but can also occur in adults. Acquired oesoph-
Fig. 4.99 Dilatation of the oesophagus on the agitis can also occur during indwelling NG tube
left side of the neck in a horse with acquired placement, especially in foals, frequent NG tube
megaoesophagus (arrows). passage or after oesophageal obstruction.