Lymphangiectasia

Signalment

• Breed predisposition:
  • Yorkshire Terrier
  • Lundehund
  • Rottweiler
  • Soft Coated Wheaten Terriers

Description

Lymphangiectasia is characterised by dilation and dysfunction of the lymphatic vessels of the intestines. Consequently, protein rich lymph leaks into the intestinal lumen, causing a protein-losing enteropathy and severe lipid malabsorption. It is relatively common in dogs but rare in cats.

Lymphangiectasia can be classified into a primary or a secondary lymphangiectasia. Primary lymphangiectasia may form part of a localised or a more widespread lymphatic abnormality. Secondary lymphangiectasia results from lymphatic obstruction, which may be caused by:

• inflammation, neoplastic infiltration or fibrosis
• thoracic duct obstruction
• right sided cardiac failure
• caval obstruction
• hepatic disease

Lymphangiectasia often accompanies a lipogranulomatous inflammation, but it is not clear which is the primary event. Lymphangitis can cause lymphatic obstruction but the leakage of lymph can also cause a granuloma to form.

Diagnosis

Clinical Signs

• Weight loss
• Chronic diarrhoea; steatorrhoea
• Ascites, oedema or chylothorax may result if there is severe hypoproteinaemia or lymphatic obstruction
• Increased appetite
• Vomiting, lethargy and anorexia (less common)

Laboratory Tests

Haematology

• Panhypoproteinaemia
• Lymphopaenia

Biochemistry

• Hypocholesterolaemia
• Hypocalcaemia due to hypoproteinaemia, vitamin D and calcium malabsorption
• Hypomagnesaemia

Other Tests

• Faecal α1-proteinase inhibitor concentrations or chromium 51-labelled albumin may be used to confirm protein-losing enteropathy.

Diagnostic Imaging

Ultrasound

Abdominal ultrasonography may reveal pleural fluid or ascites as well as helping to narrow down other differential diagnoses. Mucosa of intestinal loops may appear thickened due to oedema.

Endoscopy

Grossly, multiple white lipid droplets with prominent mucosal blebs can be seen.

Histopathology

Preferably, a full thickness biopsy is needed for a definitive diagnosis.

Refer to Lymphangiectasia for pathology

It is essential to distinguish a true lymphangiectasia from a secondary lacteal dilation due to Inflammatory Bowel Disease (IBD). In the case of IBD, inflammatory infiltrate will be seen in the lamina propria, but the degree of infiltration may be underestimated if oedema is present.

Treatment

• Identify and treat the underlying cause if it is a secondary lymphangiectasia
• Fat-restricted diet
  • The diet needs to be calorific and highly digestible
• Supplementation of fat soluble vitamins
• Anecdotal report of glutamine supplementation
• Prednisolone at 1-2 mg/kg/day PO
  • Anti-inflammatory and immunosuppressive effect may be beneficial
  • This is particularly true if there is associated lymphangitis, lipogranulomas or a lymphocytic-plasmacytic infiltration of the lamina propria.
  • Azathioprine at 2.2 mg/kg q48 hours or Ciclosporin at 3-5 mg/kg q24 to 12 hours can also be considered
• Antimicrobials such as metronidazole or tylosin
  • This may be beneficial due to their potential immunomodulatory effect and modulation of the enteric flora
• Diuretics such as frusemide and spironolactone are used to manage effusions.
• Short term treatment with plasma or colloids can be given for plasma expansion.

Prognosis

Guarded. The response to treatment is generally poor although some dogs may do well. Dogs may be in remission for several years but the disease eventually progress to fulminant hypoproteinaemia.

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.