ISSN 2398-2950      

Megacolon

ffelis
Contributor(s):

Ed Hall

Phil Nicholls


Introduction

  • Extreme dilation of the colon leading to severe constipation.
  • Cause: primary - idiopathic, may be disorder of smooth muscle function; secondary to any lesion preventing normal defecation over a long period, eg neoplasia, strictures, foreign bodies, extramural compression of colon.
  • Signs: lethargy, anorexia, constipation, ptyalism, vomiting, tenesmus.
  • Diagnosis: abdominal palpation, radiography.
  • Treatment: initially - fluid therapy, remove cause, laxatives and enemas; long-term - diet and bulk-forming agents, prokinetics, eg cisapride; surgery - subtotal colectomy for irreversible cases.
  • Prognosis: guarded depending on stage of disease and choice of treatment.

Pathogenesis

Etiology

  • Idiopathic - dysfunction of colonic smooth muscle, progressive post-receptor defect in excitation-contraction coupling.
  • Secondary to colonic obstruction - extraluminal compression, eg pelvic fracture, intraluminal masses or strictures, functional disorders, eg neuromuscular disease, congenital anomalies, metabolic disorders.

Specific

  • Colonic neoplasia, eg lymphosarcoma Lymphoma.
  • Foreign bodies.
  • Extramural colonic compression.
  • Strictures.

Pathophysiology

  • Smooth muscle dysfunction OR other primary disease   →   normal defecation prevented over prolonged period   →   colon distends   →   muscle degenerates   →   colon flaccid and filled with dry, hard fecal material.

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.
  • Bertoy R W (2002) Megacolon in the cat. Vet Clin North Am Small Anim Pract 32 (4), 901-915 PubMed.

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