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See also: '''[[Portosystemic Shunt]]'''

| See also:

| '''[[Portosystemic Shunt]]'''

==Description==

==Introduction==

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]] (PSS), microvascular dysplasia is not grossly evident and occurs due to vascular connections between microscopic blood vessels.  The defect is thought to occur at the level of the terminal portal veins.  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.   

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]] (PSS), microvascular dysplasia is not grossly evident and occurs due to vascular connections between microscopic blood vessels.  The defect is thought to occur at the level of the terminal portal veins.  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.   

==Diagnosis==

==Diagnosis==

===Clinical Signs===

===Clinical Signs===

Signs are very similar to those observed in animals with congenital portosystemic shunts, as listed [[Portosystemic Shunt#Clinical Signs|here]].  Animals with MD are often less severely affected than those with PSS and they may even by asymptomatic. Briefly, common clinical signs include:

Signs are very similar to those observed in animals with [[Portosystemic Shunt#Clinical Signs|congenital portosystemic shunts]].  Animals with MD are often less severely affected than those with PSS and they may even by asymptomatic. Briefly, common clinical signs include:

*'''Stunted growth''' compared to littermates.

*'''Stunted growth''' compared to littermates.

*Neurological signs due to '''[[Hepatic Encephalopathy]]'''.

*Neurological signs due to '''[[Hepatic Encephalopathy]]'''.

===Laboratory Tests===

===Laboratory Tests===

The results of blood tests will be similar to those obtained from animals with PSS, as described [[Portosystemic Shunt#Laboratory Tests|here]].  In some cases however, raised serum bile acid concentrations may be the only abnormality detected in young animals with MD and concentrations of albumin and cholesterol are less reliable in making a diagnosis.  Microcytic red blood cells are also an uncommon finding in animals with MD.

The results of blood tests will be similar to those obtained from [[Portosystemic Shunt#Laboratory Tests|animals with PSS]].  In some cases however, raised serum bile acid concentrations may be the only abnormality detected in young animals with MD and concentrations of albumin and cholesterol are less reliable in making a diagnosis.  Microcytic red blood cells are also an uncommon finding in animals with MD.

===Other Tests===

===Other Tests===

==Treatment==

==Treatment==

'''Medical management''' should be implemented, as for [[Portosystemic Shunt|portosystemic shunts]].

'''Medical management''' should be implemented, as for [[Portosystemic Shunt#Medical Management|portosystemic shunts]].

==Prognosis==

==Prognosis==

With symptomatic treatment for hepatic encephalopathy, animals with MD can be expected to live with good quality of life for up to 5 years <ref> Christiansen JS, Hottinger HA, Allen L, Phillips L, Aronson LR. Hepatic microvascular dysplasia in dogs: a retrospective study of 24 cases (1987-1995). J Am Anim Hosp Assoc. 2000 Sep-Oct;36(5):385-9. </ref>.

With symptomatic treatment for hepatic encephalopathy, animals with MD can be expected to live with good quality of life for up to 5 years <ref> Christiansen JS, Hottinger HA, Allen L, Phillips L, Aronson LR. Hepatic microvascular dysplasia in dogs: a retrospective study of 24 cases (1987-1995). J Am Anim Hosp Assoc. 2000 Sep-Oct;36(5):385-9. </ref>.

==References==

==References==

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[[Category:Liver_-_Developmental_Pathology]]

[[Category:Liver_-_Developmental_Pathology]]

[[Category:To_Do_-_James]]

 

[[Category:Dog]][[Category:Cat]]

[[Category:Liver Diseases - Dog]][[Category:Liver Diseases - Cat]]

[[Category:To_Do_-_Review]]

[[Category:Expert_Review]]