Inflammatory Bowel Disease

Signalment

• No sex predisposition
• More common in middle-aged dogs and cats

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.

Diagnosis

Clinical Signs

• Vomiting (most common sign in cat)
• Diarrhoea; small or large intestinal
• Haematemesis or haematochezia (more severe cases)
• Weight loss
• Abdominal discomfort or pain
• Excessive borborygmi
• Variable appetite; increased or decreased
• 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 protein source that had not previously been exposed to. Clinical signs should resolve within 1-2 weeks.
  • Folate and cobalamin supplementation may be required if the levels are subnormal.
• Antimicrobials such as metronidazole at 10-15 mg/kg BID 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 at 2.2mg/kg/day PO for 10 days. Then gradually taper to EOD.
  • 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.