Category:Intestine - Vascular Disturbances

• Vascular disturbances cause obstruction of efferent veins, blockage of afferent arteries or reduced blood flow through unobstructed circulation.
  • All have similar effects on the intestine

Effects of Intestinal Hypoxia

• Intestinal hypoxia is induced by vasular distrubances (above).
• Timescale:
  • 10 – 30 minutes - separation of epithelium from basement membrane.
  • 1 - 2 hours - villus destruction.
  • 2 hours - necrosis of crypt cells.
  • 4 - 5 hours - all mucosa necrotic, sloughed.

Intestinal Venous Congestion

Intestinal Arterial Thromboembolism

• Non-strangulation infarction.
• There is often a functional obstruction at point of infarction.
• Relatively rare as the bowel has a good anastomosing blood supply.

Thrombosis of cranial mesenteric artery caused by Strongylus vulgaris larvae (Courtesy of Bristol BioMed Image Archive)

Horses

• E.g. Strongylus vulgaris larvae migrating in cranial mesenteric artery in horse
  • Cause arteritis with thickening of wall
    • Due to fibrin and debris deposition and hypersensitivity reaction
  • Leads to vasoconstriction
    • May occlude lumen and encourage thromboemboli.
  • Can cause ischaemic necrosis of a segment of small intestine
  • Is less common now that Strongylus vulgaris infections are declining.
• E.g. equine salmonellosis.

Infarction of the small bowel (Courtesy of Bristol BioMed Image Archive)

Small Animals

• Especially dogs
• Road traffic accidents produce and infact in the gut.
• Renal disease also causes infarction.
  • Particularly nephrotic syndrome.
  • Anticoagulant proteins are lost in the urine, leading to a prothrombic state in the ciruclation.

Pathology

• Similar to that caused by venous congestion.
• See sharply delineated dark areas in bowel that are flaccid with loss of tone.
  • These become necrotic followed later by peritonitis.