Changes

===Hepatic Jaundice===

===Hepatic Jaundice===

[[Liver - Anatomy & Physiology|Liver]] cell damage may lead to jaundice by two main mechanisms:

Also referred to as '''Toxic Icterus'''. [[Liver - Anatomy & Physiology|Liver]] cell damage may lead to jaundice by two main mechanisms:

*In '''acute hepatic necrosis''' and [[Hepatic Lipidosis|'''hepatic lipidosis''']], damaged cells swell to such a degree that flow of bile in the canaliculi is obstructed.

*In '''acute hepatic necrosis''' and [[Hepatic Lipidosis|'''hepatic lipidosis''']], damaged cells swell to such a degree that flow of bile in the canaliculi is obstructed. There is therefore intrahepatic obstruction and conjugated bilirubin accumulates in the blood.

*In '''chronic [[Liver Failure|liver failure]]''', so much hepatic function is lost that the bilirubin produced by the constant turnover of red blood cells cannot be taken up and conjugated, leading to an accumulation of unconjugated bilirubin in the blood.  

*In '''chronic [[Liver Failure|liver failure]]''', so much hepatic function is lost that the bilirubin produced by the constant turnover of red blood cells cannot be taken up and conjugated, leading to an accumulation of unconjugated bilirubin in the blood.  

===Post-hepatic Jaundice===

===Post-hepatic Jaundice===

This occurs due to an obstruction in the biliary tract which normally carriers bile from the liver and gall bladder to the duodenum. Conjugated bilirubin is found in the urine but, in complete obstruction, urobilinogen will be absent from the urine and stercobilin from the faeces. Possible causes of post-hepatic jaundice include:

Also called '''Obstructive Icterus'''. This occurs due to an [[Biliary Tract - Obstruction|obstruction in the biliary tract]] which normally carriers bile from the liver and gall bladder to the duodenum. Conjugated bilirubin is found in the urine but, in complete obstruction, urobilinogen will be absent from the urine and stercobilin from the faeces. Possible causes of post-hepatic jaundice include:

*'''Intraluminal obstructions''':

*'''Intraluminal obstructions''':

**'''Choleliths''' ('gall stones') are much less common in animals than they are in humans.  They are usually composed of bilirubin salts in dogs and calcium carbonate in cats, although they are very rare in the latter species.

**'''Choleliths''' ('gall stones') are much less common in animals than they are in humans.  They are usually composed of bilirubin salts in dogs and calcium carbonate in cats, although they are very rare in the latter species.

Animals suffering from extra-hepatic biliary obstruction (EHBO) are often profoundly unwell.  The reduced flow of bile salts into the gastro-intestinal (GI) tract allows GI bacteria to proliferate and eventually translocate across the intestinal wall.  In addition, biliary stasis reduces the function of Kupffer cells within the liver, reducing their ability to remove and neutralise translocated bacteria from the portal blood.  These animals should be stabilised adequately before any surgical repair is attempted.

Animals suffering from extra-hepatic biliary obstruction (EHBO) are often profoundly unwell.  The reduced flow of bile salts into the gastro-intestinal (GI) tract allows GI bacteria to proliferate and eventually translocate across the intestinal wall.  In addition, biliary stasis reduces the function of Kupffer cells within the liver, reducing their ability to remove and neutralise translocated bacteria from the portal blood.  These animals should be stabilised adequately before any surgical repair is attempted.

Obstructive icterus results in excessive conjugated bilirubin in the blood. Out of the three types of icterus, it causes the most elevated levels of bilirubin in the blood and the greatest discoloration of the tissues of the body.

Bilirubin stains brown with H&E, like both [[Pigmentation - Pathology#Haemosiderin|haemosiderin]] and [[Pigmentation - Pathology#Lipofuscin|lipofuscin]]. They must be distinguished from each other by special stains. Bilirubin stains bright green with a Fouchet stain.

=====Van de Berg Test=====

=====Van de Berg Test=====