Changes

==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]] into the intestinal lumen, producing a [[Protein Losing Enteropathy|protein-losing enteropathy]](PLE) and severe lipid malabsorption.   

'''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 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.   

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:

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:

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

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

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

*'''Obstruction of the thoracic duct''', the major lymphatic vessel that runs through the chest.  This may occur due to rupture and subsequent inflammation or due to the presence of a neoplastic mass.

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

*'''[[Heart Failure, Right-Sided|Right-sided heat failure]]''' (including cardiac tamponade) causes an increase in central venous pressure, reducing the pressure gradient between the thoracic duct and the subclavian veins with which it anastomoses.

**'''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.

 

*caval obstruction?

**'''[[Heart Failure, Right-Sided|Right-sided heat failure]]''' due to [[Cardiomyopathies|cardiomyopathy]], [[Cardiac Tamponade|cardiac tamponade]] or [[Tricuspid Valve Dysplasia|tricuspid dysplasia]], [[Cor Pulmonale]] or Cor Triatriatum Dexter.

*hepatic disease?

**Obstruction to venous return by '''intra-thoracic masses''' including thymoma and thymic lymphoma.

==Signalment==

==Signalment==

====Endoscopy====

====Endoscopy====

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

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

===Histopathology===

===Histopathology===

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.

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.  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 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 - Pathology|oedema]] is present.

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 - Pathology|oedema]] is present.

===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 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.

===Immunosuppressive===

===Immunosuppressive===