Intestinal Obstruction

Description

Intestinal obstruction can be classified as acute or chronic, partial or complete, simple or incarcerated. The cause of the obstruction can be intraluminal, extraluminal or intramural. Most common causes of intestinal obstruction include intussusception, neoplasia and foreign body. Intussusception is more likely in young animals with a history of gastroenteritis or intestinal surgery. Cats frequently present with linear foreign bodies. Other less common causes include intestinal torsion/volvulus and incarcerated intestinal obstruction. Neoplasia is more commonly present in middle-aged to older animals.

Diagnosis

Clinical Signs

The clinical presentation depends on cause, severity, and site of obstruction. Upper small intestinal obstruction causes a net fluid secretion whereas lower small intestinal obstruction causes a net fluid resoption. Antibiotic responsive diarrhoea is more likely in distal small intestinal obstruction.

Simple obstruction

• Vomiting; the further the obstruction is towards the mouth, the more frequent and the more volume the vomiting is
• Moribund or in septic shock; if part of the intestine becomes devitalised, resulting in septic peritonitis
• Abdominal foreign body, mass or obstructive ileus may be palpable

Incarcerated intestinal obstruction

• Acute vomiting
• Abdominal pain
• Depression
• Endotoxic shock with toxic mucous membranes and tachycardia

Intestinal torsion/volvulus

Acute and severe onset of:

• nausea
• retching
• vomiting ± bloody diarrhoea
• acute abdomen
• abdominal fluid accumulation
• depression

Linear foreign body

• Vomiting; food, bile and/or phlegm
• Anorexiam, depression

Laboratory Tests

• Mild dehydration to septic shock

Biochemistry

• Hypochloraemia and hypokalaemia acid-base derangement is common in animals with upeer small intestinal obstruction.

Diagnostic Imaging

Radiography

• Plain abdominal radiography may be all that is needed to reveal the cause of the obstruction. Gas and fluid accumulation may be visible due to intestinal dilation.
• Contrast radiography may be needed if ileus and obstruction cannot easily be distinguished.

Ultrasonography

Most of the time, this is a more sensitive technique in revealing the cause of the obstruction compared to radiography. Dilation and thickening of the wall of the intestine may be visible.

Histopathology

• Fine needle aspirate may be warranted before surgery if a mass is suspected, such as lymphoma.

Treatment

Stabilisation

• Electrolyte and acid-base derangements are common in a vomiting animal. These need to be addressed prior to anaesthesia.

Surgery

• Once stabilised, the animal can be taken to surgery.

Prognosis

• Good, if there is no septic peritonitis and there is no need for a large resection of the intestines.

References

• Ettinger, S.J. and Feldman, E. C. (2000) Textbook of Veterinary Internal Medicine Diseases of the Dog and Cat Volume 2 (Fifth Edition) W.B. Saunders Company.
• Hall, E.J, Simpson, J.W. and Williams, D.A. (2005) BSAVA Manual of Canine and Feline Gastroenterology (2nd Edition) BSAVA
• Nelson, R.W. and Couto, C.G. (2009) Small Animal Internal Medicine (Fourth Edition) Mosby Elsevier.

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