Cat Megacolon – Causes, Symptoms, Diagnosis & Treatment

megacolon in cats

Megacolon is a condition in which the colon becomes abnormally dilated and enlarged and loses its ability to contract. Constipation and obstipation are associated with megacolon. 

There are two forms of megacolon; congenital (present at birth) or acquired. The most common form of acquired megacolon is  idiopathic (cause unknown) although it is believed to be improper activation of smooth muscle within the colon and rectum. [1]

Other causes  include the following:

  • Dietary, such as ingesting nondigestible objects which become impacted
  • Injury, from a pelvic fracture which causes a narrowing of the pelvis
  • Refusal to defecate because of a dirty litter tray resulting in fecal matter building up and distending the colon
  • Anal sac impaction which causes painful defecation
  • Tumours of the colon or anus which can lead to a blockage or painful defecation
  • Neurological disorders such as Manx syndrome

Megacolon can occur in cats of any age or breed, however, more cases are seen in middle-aged, male cats.

What are the symptoms of megacolon?

  • Crouching and straining for prolonged periods in the litter tray, with either no feces being passed or small, hard, dry stools.
  • Defecating outside the litter tray.
  • Lethargy.
  • Vomiting.
  • Depression.
  • Hunching over, due to discomfort.
  • Loss of appetite.
  • Weight loss.
  • Abdominal pain.

Diagnosing megacolon:

Your veterinarian will perform a complete physical examination, including a complete neurological exam.  Abdominal palpitation will reveal a hard and full colon.

Other tests he may perform include:

  • Complete blood count, biochemical profile, and urinalysis to check for metabolic reasons for dehydration such as kidney disease or diabetes mellitus.
  • Abdominal/pelvic radiographs – To assess the size of the colon and to evaluate for abnormalities of the lumbar spine and pelvis.
  • Rectal examination –  To evaluate for rectal strictures, masses, and perineal hernias.
  • Abdominal ultrasound, Contrast studies, and colonoscopy may also be performed to help determine the cause.
  • T4 test to check for hypothyroidism.

Treating megacolon:

Treatment depends on the severity of the condition and includes;

  • If possible, find and treat the cause of megacolon.
  • Enema and manual removal of the feces: This is performed with the cat under anesthesia.
  • Diet: Your veterinarian may choose to put your cat on a high fibre diet which helps create a soft stool.
  • Cisapride is an oral medication which stimulates gastrointestinal motility (muscular contractions which push the feces through the intestine).
  • Lactulose to soften the stools, making them easier to pass.
  • Colectomy: Your veterinarian may recommend a colectomy if medical management treatments have failed. This is an operation to remove part or all of the colon.


[1] The Cornell Book of Cats – P. 256

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