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Hepatic Microvascular Dysplasia (view source)
Revision as of 20:53, 10 July 2010
, 20:53, 10 July 2010no edit summary
{{unfinished}}
**Arteriolarization of central veins
==Description==
**smooth muscle proliferation (segmental) within the walls of central veins
Microvascular dysplasia (MD) is a congenital defect of the hepatic vasculature that results in abnormal communication between the portal and systemic venous circulation. Unlike [[Portosystemic Shunt|portosystemic shunting]], microvascular dysplasia is not grossly evident and occurs due to vascular connections between microscopic blood vessels. However, MD may occur in conjunction with a gross shunting vessel and it does cause clinical signs which are very similar to those observed in animals with portosystemic shunts.
**random distribution of small calibre vessels
**endothelial hyperplasia within portal triads
==Signalment==
**dilation of periacinar vascular spaces.
MD occurs as a congenital disease in several small breeds of dog, particularly the Yorksire terrier and Cairn terrier. The average age at presentation is 3 years (older than most animals presenting with congenital portosystemic shunts) and the condition is more common in female dogs than males.
**May also see decreased diameter of intrahepatic veins.
==Diagnosis==
===Clinical Signs===
Signs are very similar to those observed in animals with congenital portosystemic shunts, as listed [[Portosystemic Shunt|here]]. Briefly, these include:
*'''Stunted growth''' compared to littermates.
*Intermittent '''gastro-intestinal signs''', including vomiting and diarrhoea.
*'''Urinary tract signs''' resulting from urate urolithiasis.
*'''Prolonged recovery from sedation or anaesthesia''' due to reduced hepatic metabolism of drugs.
===Laboratory Tests===
Diagnosis relies on ruling out the presence of a gross shunting vessel by diagnostic imaging. A liver biopsy is then performed and histological analysis of the sample will show a pattern identical to that of a congenital portosystemic shunt:
*'''Arteriolarisation of central veins'''
*'''Smooth muscle proliferation''' (segmental) within the walls of central veins
*'''Random distribution of small calibre vessels'''
*'''Endothelial hyperplasia''' within portal triads
*'''Dilation of periacinar vascular spaces'''
*'''Decreased diameter of intrahepatic veins'''
Blood samples
*Higher MCV, serum postprandial bile acid concentrations, serum albumin and cholesterol concentrations when PSS and HMD together, compared to HMD alone.
*Higher MCV, serum postprandial bile acid concentrations, serum albumin and cholesterol concentrations when PSS and HMD together, compared to HMD alone.
==Treatment==
'''Medical management''' should be implemented, as for [[Portosystemic Shunt|portosystemic shunts]].
[[Category:Liver_-_Developmental_Pathology]]
[[Category:Liver_-_Developmental_Pathology]]
[[Category:To_Do_-_James]]
[[Category:To_Do_-_James]]