Difference between revisions of "Lymphangiectasia"

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{{unfinished}}
  
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==Introduction==
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{{dog}}
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'''Lymphangiectasia''' is a disease of the [[Lymphatic Vessels - Anatomy & Physiology|lymphatic vessels]] that results in the leakage of protein-rich [[Lymph - Anatomy & Physiology|lymph]].  The term is usually taken to mean intestinal lymphangiectasia (in which lymph is lost into the intestinal lumen, producing a [[Protein Losing Enteropathy|protein-losing enteropathy]](PLE) and severe lipid malabsorption) but thoracic and generalised lymphangiectasia have been reported. 
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{{cat}}
  
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Lymphangiectasia can be classified into a primary or secondary disease.  '''Primary lymphangiectasia''' usually only affects the intestine but it occasionally involves a concurrent [[Chylous Effusion|chylothorax]].  It occurs due to a congenital defect of the lymphatic vessels but it may be associated with inflammation of the lymphatics, so-called '''lipogranulomatous lympangitis'''.  The relationship between lymphangiectasia and lipogranulomatous lymphangitis is currently unclear and it is possible that either condition could result in the development of the other.  '''Secondary lymphangiectasia''' occurs with any pathological process that causes lymphatic obstruction, of which the most common are:
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==Signalment==
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*Direct damage to the lymphatics
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*Breed predisposition:
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**'''Inflammation''' and subsequent fibrosis of the lymphatics, obstructing the lumina of the vessels.
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**Yorkshire Terrier
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**'''Neoplastic infiltration or erosion''' of the walls of lymphatic vessels.
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**Lundehund
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**'''Obstruction of the thoracic duct''', the major lymphatic vessel that runs through the chest.  This may occur due to traumatic rupture or due to the presence of a neoplastic mass.
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**Rottweiler
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*Increased pressure in the systemic veins reducing the pressure gradient from the thoracic duct to the subclavian veins
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**Soft Coated Wheaten Terriers
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**'''[[Heart Failure, Right-Sided|Right-sided heat failure]]''' due to [[Cardiomyopathy|cardiomyopathy]], [[Cardiac Tamponade|cardiac tamponade]] or [[Tricuspid Valve Dysplasia|tricuspid dysplasia]], [[Cor Pulmonale]] or Cor Triatriatum Dexter.   
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**Obstruction to venous return by '''intra-thoracic masses''' including thymoma and thymic lymphoma.
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 +
==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.
  
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==Signalment==
 
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The disease is relatively common in dogs but rare in cats.  Yorkshire terriers, Rottweilers and Norwegian Lundehunds are predisposed to the development of disease.
 
  
 
==Diagnosis==
 
==Diagnosis==
 
===Clinical Signs===
 
===Clinical Signs===
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Clinical signs are related to the loss of lymph and the resultant protein-losing enteropathy and fat malabsorption.  The following signs are therefore common:
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*Weight loss
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*'''Weight loss''' in the face of '''polyphagia''' due to loss of fat and protein.
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*Chronic diarrhoea; steatorrhoea
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*'''Chronic [[Diarrhoea|diarrhoea]]''' or '''steatorrhoea''', the latter occurring due to the high fat content of the faeces.  The presence of large quantities of fat in the intestinal lumen provides a substrate for bacteria which produce hydroxy-fatty acids as by-products.  Bacterial proliferation may result in concurrent [[Antibiotic Responsive Diarrhoea|small intestinal bacterial overgrowth]] (SIBO) and the hydroxy-fatty acids act as potent secretagogues in the colon, leading to the production of diarrhoeic faeces.
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*Ascites, oedema or chylothorax may result if there is severe hypoproteinaemia or lymphatic obstruction
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*[[:Category:Effusions|'''Effusions''']] may develop for a number of reasons in animals with lymphangiectasia.  Ascites composed of a [[Transudate|transudate]] may develop in severely [[Hypoalbuminaemia|hypoproteinaemic]] animals but, in animals that develop secondary lymphangiectasia due to right-sided heart failure, a [[Modified Transudate|modified transudate]] may form due to portal hypertension.  If the major lymphatic vessels of the abdomen are disrupted (by a neoplastic mass), [[Chylous Effusion|chylous ascites]] may develop, although this is very rare.  In animals with congenital lymphangiectasia or in those with disruption of the thoracic duct, chylothorax has also been described.
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*Increased appetite
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*[[Vomiting|Vomiting]], lethargy and anorexia are uncommon clinical signs.
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*Vomiting, lethargy and anorexia (less common)
 +
 
  
 
===Laboratory Tests===
 
===Laboratory Tests===
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Several parameters may be altered on haematological or biochemical analysis of blood samples.
 
 
====Haematology====
 
====Haematology====
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'''[[Lymphopenia|Lymphopaenia]]''' occurs as lymphocytes are the major type of cell present in lymph and they are therefore lost into the intestinal lumen in large numbers.  If an inflammatory process (such as lipogranulomatous lymphangitis) has developed, there may be a '''monocytosis''' or '''neutrophilia'''.
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*'''Panhypoproteinaemia'''
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*'''Lymphopaenia'''
  
 
====Biochemistry====
 
====Biochemistry====
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Changes on biochemistry mainly reflect the loss of lymph into the intestine:
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*'''Hypocholesterolaemia'''
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*'''Panhypoproteinaemia''' occurs in most forms of protein-losing enteropathy and suggests that both plasma albumin and globulin are being lost. 
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*Hypocalcaemia due to hypoproteinaemia, vitamin D and calcium malabsorption
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*'''Hypocholesterolaemia''' and a reduction in the circulating concentration of triglycerides occur as these nutrients are lost into the intestinal lumen.
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*Hypomagnesaemia
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*'''Hypocalcaemia''' occurs due to hypoproteinaemia (reducing the total but not ionised calcium concentration) and due to vitamin D and calcium malabsorption.  Hypocalcaemic tetany may be observed in animals which are severely hypocalcaemic and which then become stressed or excited.
 
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*'''Hypomagnesaemia''' may also develop due to malabsorption but this is rarely recognised in clinical practice.
 
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*[[Antibiotic Responsive Diarrhoea|Changes associated with SIBO are discussed here]].
 
  
 
====Other Tests====
 
====Other Tests====
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Further tests may be used to confirm the presence of [[Protein Losing Enteropathy|protein-losing enteropathy]], including measurement of '''faecal alpha-1 protease inhibitor concentration''' and '''faecal 51-Chromium albumin concentration''' after intra-venous injection.
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*Faecal α1-proteinase inhibitor concentrations or chromium 51-labelled albumin may be used to confirm protein-losing enteropathy.
 +
 
  
 
===Diagnostic Imaging===
 
===Diagnostic Imaging===
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====Ultrasonography====
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====Ultrasound====
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Ultrasound scans may reveal the presence of effusions (pleural fluid or ascites) and may be used to rule out other causes of PLE.  The mucosa of affected intestinal loops may appear to be thickened and may also appear to have 'tiger stripes', although the latter finding is an unreliable indicator of lymphangiectasia.  
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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====
 
====Endoscopy====
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[[Image:Lymphangiectasia.jpg|thumb|right|300px|Endoscopy of a dog with lymphangiectasia, showing protrusion of lipid droplets into the intestinal lumen.<br><small>Copyright Karin Allenspach 2007 RVC]]</small>
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Grossly, multiple white lipid droplets with prominent mucosal blebs can be seen.
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Grossly, multiple white lipid droplets can be seen to protrude from prominent mucosal blebs in the intestine (see image).  The mucosa is frequently oedematous.
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===Histopathology===
 
===Histopathology===
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Preferably, a full thickness intestinal biopsy should be taken to achieve a definitive diagnosis.  Care should be taken as hypoproteinaemic animals are at much greater risk of dehiscence at the biopsy sites, potentially leading to an acute septic [[Peritonitis - Cats and Dogs|peritonitis]].  On histological examination of the biopsy sample, accumulation of lipid-laden macrophages may be detected together with a granulomatous response around distended lymphatics.
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Preferably, a full thickness biopsy is needed for a definitive diagnosis.
  
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It is essential to distinguish a true lymphangiectasia from secondary lacteal dilation that occurs with [[Inflammatory Bowel Disease|Inflammatory Bowel Disease]] (IBD).  In the case of IBD, an inflammatory infiltrate will be seen in the lamina propria but the degree of infiltration may be underestimated if [[Oedema|oedema]] is present.
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Refer to [[Intestines Inflammatory Bowel Disease And Related Conditions - Pathology #Lymphangiectasia|Lymphangiectasia]] for pathology
  
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==Treatment==
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It is essential to distinguish a true lymphangiectasia from a secondary lacteal dilation due to [[Inflammatory Bowel Disease - WikiClinical|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.
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If the lymphangiectasia is secondary to another disease, the underlying cause should be treated.  Otherwise, the following elements should be considered in designing a treatment plan.
 
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===Dietary modification===
 
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The diet should have a '''low fat content''' to reduce the production of lymph but should have a high calorie content to allow the animal to regain weight.  The fat soluble vitamins (K, E, D and A) should be supplemented and additional calcium should be added if hypocalcaemia is documented.
 
  
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===Immunosuppressive===
 
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Immunosuppressive agents are a key element in the treatment of lymphangiectasia.  Corticosteroids such as [[Steroids|prednisolone]] are used most commonly for this pupose at an immunosuppressive dose (of 1-2 mg/kg/day in dogs).  These drugs are likely to be of most benefit in those animals that have evidence of inflammatory pathology, such as lipogranulomatous lymphangitis and inflammatory infiltration of the lamina propria.  If further immunosuppression is considered necessary or if adverse effects occur with corticosteroid therapy, azathioprine or ciclosporin could also be used.
 
  
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===Antimicrobials===
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==Treatment==
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[[Nitroimidazoles|Metronidazole]] or [[Macrolides and Lincosamides|tylosin]] may be used to control any secondary [[Antibiotic Responsive Diarrhoea|SIBO]].  Antibiotics are thought to have effects on both the intestinal immune system and the normal enteric flora.
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*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.
  
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===Fluid therapy===
 
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Short term treatment with plasma or [[Colloids|colloids]] can be instituted in severely hypoproteinaemic animals that have begun to develop clinical signs.  Diuretics such as [[Heart Failure, Treatment#C. Pharmacological|frusemide and spironolactone]] may also be used to manage effusions.
 
  
 
==Prognosis==
 
==Prognosis==
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The long-term prognosis is guarded as, although animals may respond to medical therapy initially, they frequently relapse and develop clinical signs associated with hypoproteinaemia.
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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.
  
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{{Learning
 
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|Vetstream = [https://www.vetstream.com/canis/Content/Disease/dis02922.asp, Canine lymphatic diseases]
 
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|literature search = [http://www.cabdirect.org/search.html?rowId=1&options1=AND&q1=Lymphangiectasia&occuring1=title&rowId=2&options2=AND&q2=&occuring2=freetext&rowId=3&options3=AND&q3=&occuring3=freetext&x=54&y=14&publishedstart=yyyy&publishedend=yyyy&calendarInput=yyyy-mm-dd&la=any&it=any&show=all Lymphangiectasia publications]
 
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}}
 
  
 
==References==
 
==References==
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*Hall, E.J, Simpson, J.W. and Williams, D.A. (2005) '''BSAVA Manual of Canine and Feline Gastroenterology (2nd Edition)''' ''BSAVA''
 
*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''.
 
*Nelson, R.W. and Couto, C.G. (2009) '''Small Animal Internal Medicine (Fourth Edition)''' ''Mosby Elsevier''.
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{{review}}
 
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==Webinars==
 
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<rss max="10" highlight="none">https://www.thewebinarvet.com/gastroenterology-and-nutrition/webinars/feed</rss>
 
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[[Category:Intestine_-_Inflammatory_Pathology]]
 
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[[Category:Intestinal Diseases - Dog]][[Category:Intestinal Diseases - Cat]]
 
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[[Category:Expert_Review]]
 

Revision as of 13:42, 12 August 2009


 This article is still under construction.


Category:WikiClinical CanineCow
Category:WikiClinical FelineCow

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.
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