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| − | ==[[Liver, Congenital Cysts]]== | + | {{frontpage |
| | + | |pagetitle =Liver - Developmental Pathology |
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| | + | <categorytree mode=pages>Liver - Developmental Pathology</categorytree> |
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| − | ==[[Liver Displacement]]==
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| − | ==[[Liver Torsion]] ==
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| − | ==[[Liver Rupture]]==
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| − | ==[[Liver Tension Lipidosis]]==
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| − | ==[[Liver Fibrosis, Capsular]] fibrosis==
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| − | == Portosystemic shunt ==
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| − | *seen in dogs and cats
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| − | *Inherited in Irish wolfhounds
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| − | **Not known what mode of inheritance in this breed
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| − | *these are vessles that allow the blood in the portal vein to bypass the [[Liver - Anatomy & Physiology|liver]] tissue (parenchyma)
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| − | *congenital
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| − | **shunting from the portal vein directly into the vena cava, azygos or renal vein
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| − | **this is the common type seen in small dogs and cats - usually a single communication between the vessels, occasionally multiple
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| − | **larger breeds tend to have the shunting to the vena cava take place within the [[Liver - Anatomy & Physiology|liver]] itself (persistent ductus venosus)
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| − | *acquired
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| − | **due to hepatic fibrosis whcih results in increased resistance of flow of blood into the [[Liver - Anatomy & Physiology|liver]] from the portal vein
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| − | **produces hypertension in the portal vein and fluid accumulates in the peritoneal cavity - '''ascites'''
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| − | **several thin-walled tortuous vessels may be seen connecting the mesenteric veins to the vena cava, and the [[Liver - Anatomy & Physiology|liver]] looks atrophic and fibrosed
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| − | *Bacteraemia is a common finding in severe hepatic disease and PSS in humans
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| − | **portal or systemic
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| − | **usually Gram-negatives
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| − | **also seen in dogs with PSS
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| − | **presumably due to reduced effectiveness of phagocytic activity in these [[Liver - Anatomy & Physiology|livers]]
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| − | **or due to shunting of blood around the liver
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| − | NB: portosystemic shunt is a major cause of hepatic encephalopathy (need link), therefore the affected animals are stunted and seem dull or stupid because of the toxic substances in their systemic circulation
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| − | == Hepatic microvascular dysplasia ==
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| − | *Small intrahepatic portal vessels and portal endothelial hyperplasia which allows abnormal communication between portal and systemic circulation.
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| − | *Can develop as a separate entity or in conjunction with a portosystemic shunt.
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| − | *Can cause c/s similar to those of PSS.
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| − | *[[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|Vomiting]], [[Diarrhoea|diarrhoea]], [[Urinary System - Anatomy & Physiology|urinary tract]] changes associated with ammonium biurate urolithiasis, stunted growth, prolonged recovery from anesthesia.
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| − | *Average age of presentation =3yrs.
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| − | *Mainly small dogs, esp. Yorkies
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| − | *Females>males
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| − | ===Histology===
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| − | **Arteriolarization of central veins
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| − | **smooth muscle proliferation (segmental) within the walls of central veins
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| − | **random distribution of small calibre vessels
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| − | **endothelial hyperplasia within portal triads
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| − | **dilation of periacinar vascular spaces.
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| − | **May also see decreased diameter of intrahepatic veins.
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| − | *Can’t be accurately distinguished from PSS alone.
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| − | *Seen in older dogs than PSS
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| − | *Higher MCV, serum postprandial bile acid concentrations, serum albumin and cholesterol concentrations when PSS and HMD together, compared to HMD alone.
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| − | == Idiopathic noncirrhotic portal hypertension ==
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| − | JAVMA paper
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| − | *Portal hypertension
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| − | *Sustained impairment of forward venous flow anywhere along the path from the portal vein to the right side of the heart.
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| − | *Luminal (thrombosis, parasites) or extraluminal obstruction (hepatic fibrosis or nodular regeneration) or relative restriction of flow due to massive portal volume overload (arterioportal fistulas).
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| − | *Hepatomegaly associated with posthepatic obstruction
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| − | *Microhepatica – associated with prehepatic/hepatic causes.
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| − | *Hepatic encephalopathy and GI bleeding not associated with posthepatic causes.
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| − | *Most common causes are RHS heart failure and severe diffuse hepatobiliary disease that results in cirrhosis.
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| − | ===Histology===
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| − | *indistinguishable from microvascular dysplasia or surgically created portosystemic shunts
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| − | **Portal triad arteriole proliferation
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| − | **portal veins small to large
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| − | **variable portal triad fibrosis
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| − | **hepatic lobule size variation
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| − | **arterioles scattered throughout hepatic parenchyma
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| − | **portal veins – small
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| − | **expanded perivenular connective tissue by arterioles and distended lymphatics.
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| | [[Category:Liver_-_Pathology]] | | [[Category:Liver_-_Pathology]] |