ISSN 2398-2977      

Esophagus: megaesophagus

pequis
Contributor(s):

Prof Jonathon Naylor


Introduction

  • Megaesophagus is generally a developmental disorder.
  • Cause: failure of peristalsis and dilation in the proximal portion of the esophagus.
  • Signs: include recurrent bouts of esophageal obstruction and aspiration pneumonia.
  • Diagnosis: requires plain and contrast radiography.
  • Treatment: untreatable.
  • Prognosis: guarded.

Pathogenesis

Etiology

  • This is a very rare disease.
  • Most cases have developmental basis and are recognized in young animals.
  • A minority of cases may be secondary to other diseases that cause neuromuscular dysfunction such as:
    • diseases causing polyneuritis.
    • diseases causing polyneuropathies.
    • Hypoadrenocorticism.
    • Hypothyroidism.
    • Grass sickness.   Grass sickness 

Predisposing factors

General

Specific

  • Grass sickness   Grass sickness  .
  • Hypoadrenocorticism.
  • Hypothyroidism.

Pathophysiology

  • Neuromuscular dysfunction causes loss of contractility of the esophageal musculature.
  • This most commonly affects the proximal striated portion.
  • Neuromuscular dysfunction causes motor insufficiency of the esophagus.
  • In cases that occur post esophageal impactions with stricture formation, ballooning and resultant megeasophagus can occur proximal to the stricture.
  • The proximal portion of the esophagus which consists of striated muscle is most usually involved.
  • Failure of peristalsis results in insufficient movement of ingesta.
  • Esophageal impaction can result.
  • Episodes of weak reverse peristalsis may occur during episodes of "choking".
  • Aspiration of ingesta results in pneumonia.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Boerma S, Back W & Sloet van Oldruitenborgh-Oosterbaan M M (2012) The Friesian horse breed: A clinical challenge to the equine veterinarian? Equine Vet Educ 24 (2), 66-71 VetMedResource.
  • Whitechair K et al (1989) What is your diagnosis? Dilatation of the thoracic portion of the esophagus. JAVMA 194 (3), 413-414 PubMed.
  • Greet T R (1982) Observations on the potential role of the oesophageal radiography in the horses. Equine Vet J 14 (1), 73-79 PubMed.

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