Protein Losing Enteropathy

Signalment

Breed predisposition:

Description

Protein-losing enteropathy (PLE) can result from any intestinal disease which produces sufficient inflammation, congestion or bleeding. This causes protein to leak into the intestines, which exceeds capacity of the gut lumen protein synthesis. Hence, there are numerous causes of PLE, including lymphangiectasia, infectious causes, structural causes, neoplasia, inflammation, endoparasites and gastrointestinal haemorrhage.

The major causes of PLE in adult dogs are inflammatory bowel disease (IBD), alimentary tract lymphoma, fungal infections (e.g. histoplasmosis). Other causes include ulcerations or erosions, severe disease of intestinal crypts and parasites. The most common causes in very young dogs are hookworms and chronic intussusception. Chronic intussusception results from acute enteritis which has not resolved completely. The animal shows some clinical improvement but diarrhoea still continues. PLE is less common in cats than dogs, and most often caused by alimentary tract lymphoma and IBD. Cats almost never suffer from lymphangiectasia, and rarely have severe parasitic infection severe enough to cause PLE. Non-intestinal diseases can be associated with PLE include ]congestive heart failure, caval obstruction and portal hypertension. However, these animals usually present with ascites rather than diarrhoea.

Diagnosis

Clinical Signs

Weight loss (predominant feature)
Vomiting and diarrhoea ± melena
Oedema, ascites and pleural effusion
Thickened intestines
Thromboembolic disease if procoagulants predominant due to loss of anticoagulant

Laboratory Tests

Haematology

Panhypoproteinaemia
- Hepatic insufficiency and protein-losing nephropathy should also be pursued with hypoalbuminaemia.
Lymphopaenia

Biochemistry

Hypocholesterolaemia
Hypocalcaemia

Other Tests

Measurement of faecal loss alpha1-protease inhibitor

Diagnostic Imaging

Radiography

Abdominal radiographs are usually unremarkable.
Thoracic radiographs may show pleural effusion, metastatic neoplasia or eveidence of histoplasmosis.

Ultrasonography

This may reveal thickening of intestines, mesenteric lymphadenopathy or abdominal effusion.

Histopathology

Endoscopically-guided multiple biopsies are useful. Surgical biopsy may be required for a definitive diagnosis of lymphoma and secondary lymphangiectasia. A small fatty meal could be given the night before biopsy to increase the chance of diagnosing lymphangiectasia.

Treatment

Plasma transfusion

This may be used to increase plasma volume. However, much of the albumin is lost in the gut and a substantial amount fails to remain in the intravascular compartment. Therefore, the extent of increase in serum albumin level is not great.
Administration of colloid may be more suitable if it is essential to increase the plasma oncotic pressure.

Diuretics

This can be used to reduce ascites.
Spironolactone 1-2 mg/kg PO BID may be more effective than frusemide.

Prognosis

This depends on the underlying cause.

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.
Willard, M. (2005) Protein-Losing Enteropathy in Dogs and Cats 30th World Congress of the WSAVA.