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==Description==

==Description==

'''Lymphangiectasia''' is a disease of the intestinal [[Lymphatic Vessels - Anatomy & Physiology|lymphatic vessels]] that results in the leakage of protein rich [[Lymph - Anatomy & Physiology|lymph]] leaks into the intestinal lumen, producing a [[Protein Losing Enteropathy|protein-losing enteropathy]](PLE) and severe lipid malabsorption.   

'''Lymphangiectasia''' is a disease of the intestinal [[Lymphatic Vessels - Anatomy & Physiology|lymphatic vessels]] that results in the leakage of protein-rich [[Lymph - Anatomy & Physiology|lymph]] into the intestinal lumen, producing a [[Protein Losing Enteropathy|protein-losing enteropathy]](PLE) and severe lipid malabsorption.   

Lymphangiectasia can be classified into a primary or a secondary disease.  '''Primary lymphangiectasia''' usually only affects the intestine but it occasionally involve 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 with 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:

Lymphangiectasia can be classified into primary or secondary disease.  '''Primary lymphangiectasia''' usually only affects the intestine but it occasionally involve 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:

*'''Inflammation''' and subsequent fibrosis of the lymphatics, obstructing the lumina of the vessels.

*'''Inflammation''' and subsequent fibrosis of the lymphatics, obstructing the lumina of the vessels.

*'''Neoplastic infiltration or erosion''' of the walls of lymphatic vessels.

*'''Neoplastic infiltration or erosion''' of the walls of lymphatic vessels.

*'''Weight loss''' in the face of '''polyphagia''' due to loss of fat and protein.

*'''Weight loss''' in the face of '''polyphagia''' due to loss of fat and protein.

*'''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 small intestinal bacterial overgrowth (SIBO) and the hydroxy-fatty acids act as potent secretagogues in the colon, leading to the production of diarrhoeic faeces.

*'''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 small intestinal bacterial overgrowth (SIBO) and the hydroxy-fatty acids act as potent secretagogues in the colon, leading to the production of diarrhoeic faeces.

*'''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 may also be described.

*'''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.

*[[Stomach and Abomasum Consequences of Gastric Disease - Pathology|Vomiting]], lethargy and anorexia are not common clinical signs.

*[[Stomach and Abomasum Consequences of Gastric Disease - Pathology|Vomiting]], lethargy and anorexia are uncommon clinical signs.

===Laboratory Tests===

===Laboratory Tests===

====Haematology====

====Haematology====

*'''[[Changes in Inflammatory Cells Circulating in Blood - Pathology #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.

*'''[[Changes in Inflammatory Cells Circulating in Blood - Pathology #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 has developed (such as lipgranulomatous lymphangitis), there may be a '''monocytosis''' or '''neutrophilia'''.

*If an inflammatory process (such as lipgranulomatous lymphangitis) has developed, there may be a '''monocytosis''' or '''neutrophilia'''.

====Biochemistry====

====Biochemistry====

*'''Panhypoproteinaemia''' occurs in most forms of protein-losing enteropathy and refers to the loss of both plasma albumin and globulin.   

*'''Panhypoproteinaemia''' occurs in most forms of protein-losing enteropathy and suggests that both plasma albumin and globulin are being lost.   

*'''Hypocholesterolaemia''' and a reduction in the circulating concentration of triglycerides occur as these nutrients are lost into the intestinal lumen.

*'''Hypocholesterolaemia''' and a reduction in the circulating concentration of triglycerides occur as these nutrients are lost into the intestinal lumen.

*[[Hypocalcaemia - Small Animal|'''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.

*[[Hypocalcaemia - Small Animal|'''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.

====Endoscopy====

====Endoscopy====

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

Grossly, multiple white lipid droplets can be seen to protrude from prominent mucosal blebs. The mucosa is frequently oedematous.

 

===Histopathology===

===Histopathology===

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

Preferably, a full thickness 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.  On histological examination of the biopsy sample, accumulation of lipid-laden macrophages may be detected together with a granulomatous response around distended lymphatics.

 

 

It is essential to distinguish a true lymphangiectasia from a secondary lacteal dilation due to [[Inflammatory Bowel Disease|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 - Pathology|oedema]] is present.

==Treatment==

==Treatment==

*Identify and treat the underlying cause if it is a secondary lymphangiectasia

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.

===Dietary modification===

===Dietary modification===

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.

*The diet needs to be calorific and highly digestible

 

*Supplementation of fat soluble vitamins

*Anecdotal report of glutamine supplementation

*Anecdotal report of glutamine supplementation

===Immunosuppressive===

===Immunosuppressive===

*[[Steroids|Prednisolone]]

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 (~2 mg/kg/day in dogs).  These drugs are likely to be of most benefit in those animals that 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.

*[[Anti-Inflammatory Drugs|Anti-inflammatory]] and immunosuppressive effect may be beneficial.

*This is particularly true if there is associated lymphangitis, lipogranulomas or a [[Enteritis, Lymphocytic - Plasmacytic |lymphocytic-plasmacytic]] infiltration of the lamina propria.

*Azathioprine or Ciclosporin can also be considered

===Antimicrobials===

===Antimicrobials===

*[[Nitroimidazoles|Metronidazole]] or [[Macrolides and Lincosamides|tylosin]] can be given

[[Nitroimidazoles|Metronidazole]] or [[Macrolides and Lincosamides|tylosin]] may be used to control any secondary [[Small Intestinal Bacterial Overgrowth and Antibiotic Responsive Diarrhoea|SIBO]].  Antibiotics are thought to have effects on both the intestinal immune system and the normal enteric flora.

*This may be beneficial due to their potential immunomodulatory effect and modulation of the enteric flora

*Diuretics such as [[Heart Failure, Treatmen#C. Pharmacological|frusemide and spironolactone]] are used to manage effusions.

===Fluid therapy===

===Fluid therapy===

*Short term treatment with [[Plasma - WikiBlood|plasma]] or [[Colloids|colloids]] can be given for plasma expansion.

Short term treatment with [[Plasma - WikiBlood|plasma]] or [[Colloids|colloids]] can be instituted in severely hypoproteinaemic animals that have begun to develop clinical signs.  Diuretics such as [[Heart Failure, Treatmen#C. Pharmacological|frusemide and spironolactone]] may also be used to manage effusions.

 

==Prognosis==

==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.

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.

 

 

 

 

 

 

 

 

==References==

==References==

[[Category:Intestine_-_Inflammatory_Pathology]]

[[Category:Intestine_-_Inflammatory_Pathology]]

[[Category:To_Do_-_James]]

[[Category:To_Do_-_James]]