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pneumonia (especially but not limited to ○ Feed several small meals per day to PEARLS & CONSIDERATIONS
right middle lung lobe; need ventrodorsal, minimize retention of large amounts in Comments
VetBooks.ir • Contrast esophagram (radiographs) • Prokinetic drugs may be tried. • Some drugs (especially sedatives like ketamine Diseases and Disorders
esophagus.
dorsoventral, or left lateral projection to
reliably see).
○ Only indicated when gastroesophageal
and alpha-2 adrenergic agonists xylazine and
○ Not needed if plain films show
megaesophagus reflux is suspected; increases normograde medetomidine) cause esophageal weakness,
which can complicate the diagnosis.
gastric emptying and reduces volume of
○ Indicated if plain films are not diagnostic acid reflux. Prokinetic drugs are often • Megaesophagus spontaneously resolves in
of esophageal disease or esophageal useful for treating gastric motility disor- some dogs.
weakness cannot be distinguished from ders, but they do not increase esophageal • Radiography/fluoroscopy is typically pre-
esophageal obstruction motility to any appreciable degree. Typical ferred to diagnose functional problems such
• Contrast esophagram using fluoroscopy options: as megaesophagus; endoscopy is preferred to
is most sensitive test for megaesophagus ■ Cisapride 0.1-0.5 mg/kg PO q 8-12h. diagnose anatomic esophageal problems such
but is usually unnecessary. Segmental Cisapride increases lower esophageal as strictures, foreign bodies, and esophagitis.
esophageal weakness (especially cervical tone (most effective gastric prokinetic), • The severity of radiographic esophageal
esophagus) and partial loss of muscular which can worsen clinical signs if dilation is not always proportional to the
tone can be especially difficult to diagnose gastroesophageal reflux is not occurring. severity of clinical signs.
(p. 1062). ■ Metoclopramide 0.2-0.4 mg/kg PO, • Mild aspiration pneumonia is often missed on
IM, or SQ q 8-12h. The increase lateral radiographs; dorsoventral and opposite
Advanced or Confirmatory Testing in lower esophageal sphincter tone lateral projections increase sensitivity.
• Antibodies against acetylcholine receptors described for metoclopramide is not • Unexplained bacterial pneumonia in a
for diagnosis of myasthenia gravis (acquired thought to be clinically significant dog could be caused by occult esophageal
megaesophagus) (p. 668) and does not contraindicate use in dysfunction; consider performing a contrast
• Resting serum cortisol concentration ± megaesophagus. esophagram to look for esophageal weakness
ACTH stimulation test to identify hypo- • Gastric acid–reducing therapy: recommended in dogs with unexplained pneumonia even
adrenocorticism in dogs with acquired if gastroesophageal reflux is likely; omeprazole if esophageal dilation is absent on plain
megaesophagus (pp. 512 and 1300) 1-2 mg/kg PO q 12h radiographs.
• Serum creatine kinase determination: various • If a dog with megaesophagus vomits per-
myopathies Chronic Treatment sistently, esophagitis typically occurs due
• Electromyography/motor nerve conduction • Ongoing implementation of measures to gastric acid entering and not exiting the
velocity: polymyopathy/polyneuropathy described in acute treatment esophageal lumen.
• Other tests as suggested by other findings • Treat any identified specific conditions (e.g., • Surgery (cardiomyotomy) has not been com-
(e.g., lead level, antinuclear antibody test) hypoadrenocorticism, myasthenia gravis). monly used in dogs with megaesophagus;
• Gastrostomy tube (p. 1109) is rarely required the role of true achalasia (which is helped
TREATMENT but can minimize regurgitation of food by such surgery) is undetermined in dogs.
(especially if patient is having major problems
Treatment Overview with aspiration and is waiting for treatment Prevention
Treat acquired megaesophagus by resolving the of underlying cause to succeed) Do not breed animals with known history of
underlying cause (possible in approximately ○ Patient can still swallow, regurgitate, and producing litters with megaesophagus.
15%-20% of dogs); treat aspiration pneumonia aspirate saliva and other material despite
if present. If an underlying cause cannot be gastrostomy tube Technician Tips
found, treat as idiopathic megaesophagus by • Select dogs may improve after treatment with Watch closely for signs of aspiration (coughing,
minimizing regurgitation with modified feeding sildenafil, cisapride, or maropitant. nasal discharge, tachypnea, dyspnea) in dogs
practices and treating aspiration pneumonia with known esophageal dysfunction or neuro-
when present. Possible Complications muscular diseases that may cause esophageal
• Aspiration pneumonia weakness.
Acute General Treatment • Infected stoma (gastrostomy tube)
• Treat pneumonia if present (p. 793). Client Education
• Treat underlying cause if found. PROGNOSIS & OUTCOME • Provide client with an education sheet: How
• Feeding modification to Provide Elevated Feedings.
○ Feed from an elevated platform so that • If the underlying cause can be found and • In cases with percutaneous endoscopic
the patient’s esophagus is perpendicular cured, the outlook can be good. Esophageal gastrostomy tube placement, provide client
to the floor and gravity aids in food/ function may normalize: with an education sheet: How to Use and
water passage from the esophagus into ○ In some dogs with congenital megaesopha- Care for an Indwelling Feeding Tube.
the stomach. Maintain this position for gus • Aspiration pneumonia can occur at any time,
5-10 minutes after eating to enhance ○ With resolution of myasthenia gravis, even in dogs with mild radiographic signs
food emptying into the stomach. The toxicity, botulism, or esophagitis of megaesophagus.
animal needs to be in a nearly perfectly • As long as megaesophagus persists, aspiration
upright position; a 50°-60° incline is often poses a risk of pneumonia and death. SUGGESTED READING
insufficient. Bailey chair can be used for • If the underlying cause cannot be resolved, McBrearty AR, et al: Clinical factors associated with
feeding. the outlook is guarded because these patients death before discharge and overall survival time in
○ Feed different consistencies of food to often die of aspiration pneumonia. Conserva- dogs with generalized megaesophagus. J Am Vet
find which is best tolerated: some animals tive management benefits many patients if Med Assoc 238:1622-1628, 2011.
fare better on canned or solid food or the clients are determined and aggressive AUTHOR: Michael D. Willard, DVM, MS, DACVIM
meatballs, whereas others do better with about making the patient eat in an almost EDITOR: Rance K. Sellon, DVM, PhD, DACVIM
gruel. perpendicular position.

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