Inflammatory Bowel Disease

Signalment

• No sex predisposition
• There are contraditions with regard to age predisposition

Description

Inflammatory bowel disease (IBD) is an idiopathic group of disorders characterised by intestinal inflammatory changes, associated with persistent or recurrent gastrointestinal signs. IBD can affect any part of the intestines and is classified according to the predominant cellular inflammatory infiltration. Several histological types have been recognised, which are:

• Lymphocytic - Plasmacytic Enteritis (LPE)
• Eosinophilic Enteritis (EE)

There is no underlying cause of IBD in 75% of cases. They are thought to reflect an exaggerated or inappropriate response by the immune system to dietary, bacterial or self-antigens. IBD is a diagnosis of exclusion. Other differential diagnoses have to be investigated and ruled out before a diagnosis of IBD can be made.

Diagnosis

Clinical Signs

• Vomiting; very common in cat, more common than diarrhoea
• Diarrhoea; very common in dog, more common than vomiting, usually small intestinal
• Weight loss; nearly all cases of chronic small intestinal disease
• Variable appetite; increased or decreased which relates to severity
• Lethargy; common in severe cases
• Anorexia; common in severe cases
• Antibiotic responsive diarrhoea
• Abdominal discomfort or pain
• Excessive borborygmi
• Haematemesis or haematochezia (more severe cases)
• Hypoproteinaemia or ascites
• Thickened intestinal loop

Laboratory Tests

Haematology

• Neutrophilia ± mild left shift in LPE
• Eosinophilia
  • Not always present in EE

Biochemistry

• Panhypoproteinaemia
• Hypocholesterolaemia
• Mild increased in liver enzymes, secondary to intestinal inflammation

Other Tests

• Faecal analysis should be carried out to rule out parasitic causes such as hookworms, whipworms and Giardia.
• Serum folate level decreases with proximal small intestinal inflammation.
• Serum cobalamin level decreases with distal small intestinal inflammation.

Diagnostic Imaging

• Plain radiography is used to evaluate for anatomic abnormalities.
• Contrast study is only valuable if there is a severe mucosal disease.
• Ultrasonography may reveal mesenteric lymphadenopathy and thickening of the intestinal wall.

Histopathology

A biopsy of the intestine is required for a definitive diagnosis of IBD. A non-invasive biopsy may be taken via endoscopy. However, this limits where the samples can be taken from as the jejunum and ileum is not easily accessible. Exploratory laparotomy and full thickness biopsy may be preferred at times.

Treatment

• Dietary modification
  • An elimination diet should be instigated. The patient should be fed strictly on a novel protein source that had not previously been exposed to. Clinical signs should resolve within 1-2 weeks. The patient should ideally be rechallenged to demonstrate a true dietary hypersensitivity.
  • Folate and cobalamin supplementation may be required if the levels are subnormal.
• Antimicrobials such as metronidazole for 3-4 weeks
  • This may be suitable for mild to moderate cases, and especially in cats.
  • The mucosal damage caused by IBD may decrease the animal's ability to manage to intestinal flora, resulting in secondary ARD has been reported.
• Immunosuppressive therapy
  • This should be used if other treatments are inadequate.
  • Prednisolone
  • Azathioprine or Cyclosporine can be given alternatively if the patient is non-responsive or unable to tolerate steroid.

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.