Intussusception

Diagram of intussuscception (Courtesy of Elspeth Milne)

• Telescoping of one segment of the bowel into another.
• Occurs in all species.
  • Particularly in young dogs.
• Can occur in the small intestine, caecum or colon.

Clinical

• Intussusception is a less acute type of obstruction.
• Produces intermittent diarrhoea.
• Animals go downhill in a few days.
• Palpation of abdomen may allow a "Cumberland sausage" effect to be felt.
  • NB abdominal palpation in small animal, rectal palpation in large animal.

Pathogenesis

• Proximal intestine invaginates into lower part of intestine.
  

  Intersusception (Courtesy of Bristol BioMed Image Archive)
  • Takes mesenteric attachment with it.
• Compression of the mesenteric vessels obstructs venous drainage of the gut, resulting in venous congestion.
  • Swelling (oedema/congestion) arises.
    • Inflammatory exudate from serous surface.
      • Fibrinous adhesions form between surfaces making structure irreducible.
• May progress to necrosis and gangrene of the tissue.
• There is often functional obstruction to bowel.
• May rupture, leading to peritonitis and death.
• Associated with anything that raises peristalsis e.g. change in diet, bacterial infection.
  • Foreign body
  • Intramural abscess/tumour
  • Heavy parasitism
  • Previous intestinal surgery
  • Enteritis
  • Other motility disorders.
  • Change in diet
  • Bacterial infection

Pathology

• When operate or at post mortem see large sausage shaped distension of length of intestine.

• Intussusception may occur post mortem
  • There are no associated changes
  • The condition is easilt reducible.