Canis ISSN: 2398-2942

Intestine: strangulated obstruction (hernia)

Contributor(s): Rachel Burrow, James Simpson

Introduction

  • Cause: a piece of intestines passes through a congenital or acquired defect in the abdominal wall, perineal musculature, mesentery, umbilicus or diaphragm.
  • Signs: vomiting, abdominal pain, anorexia, and depression.
  • Strangulation should always be considered in cases of suspected intestinal obstruction where the clinical signs are more acute and severe than those usually associated with a simple mechanical obstruction, and in those cases that respond poorly to initial stabilization.
  • Diagnosis: radiography, surgery.
  • Treatment: surgical exposure of the strangulation, breakdown of any adhesions and reduction of the herniated intestines, and possibly resection of devitalized intestines and anastomosis.
  • Prognosis: guarded-poor if large amount of intestines involved and the patient is in endotoxic shock. The prognosis is good if there has been minimal vascular damage to the herniated small intestines and the patient is cardiovascularly stable at time of surgery.

Pathogenesis

Etiology

  • If there is a defect or hernia within the physical boundaries of the abdomen, or a defect in the mesentery, a loop of intestines may pass through the hernia or defect. Strangulation occurs if the blood supply to that loop of intestines becomes compromised by twisting or by external pressure where the intestinal loop passes through the hernia or defect.

Specific

  • Existing abdominal wall, diaphragmatic, perineal or mesenteric defect (including ruptures or hernias).

Pathophysiology

  • Luminal obstuction of the intestine as such is not always present, but the blood supply to a segment of herniated intestines is compromised by twisting of the vessels supplying that portion of intestines, or by pressure applied by the tissue through which the intestines has herniated.
  • The lower pressure intestinal veins will become obstructed first, an intact arterial supply will allow the initial continued arterial blood flow with intramural sequestration of blood and eventually intestinal wall edema, which will progress to mucosal sloughing and leakage of blood into the intestinal lumen so that the fluid intestinal luminal fluid in a strangulated obstruction will contain a significant amount of blood.
  • The intestines will distend and become filled with gas and fluid proximal to the strangulation.
  • If the strangulation continues, the bowel wall will become non-viable and necrotic, allowing the transmural migration of toxins and bacteria. Fluid and blood loss combined with the peritoneal absorption of these bacteria and toxic substances will eventually lead to hypovolemia and endotoxic shock and death if left untreated.

Timecourse

  • Acute.

Diagnosis

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Treatment

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Prevention

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Cair√≥ J, Font J, Gorraiz J, Martin N & Pons C (1999) Intestinal volvulus in dogs - a study of four clinical cases. JSAP 40 (3), 136-140 PubMed.

Other sources of information

  • Read R A, Bellenger C R (2003)Hernias.In: Slatter D (ed)Textbook of Small Animal Surgery3rd Edn. Philadelphia, W B Saunders, pp 446-448.
  • Smeak D D (2003)Abdominal hernias.In: Slatter D (ed)Textbook of Small Animal Surgery3rd edn. Philadelphia, W B Saunders, pp 449-470.
  • Hunt G Bet al(2003)Diaphragmatic, Pericardial and Hiatal Hernia.In: Slatter D (ed)Textbook of Small Animal Surgery3rd edn. Philadelphia, W B Saunders, pp 471-487.
  • Brown D (2003)Small Intestines.In: Slatter D (ed)Textbook of Small Animal Surgery3rd edn. Philadelphia, W B Saunders, pp 644-664.


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