Changes

Also known as: '''''Jaundice

Also known as: '''''Jaundice

==Causes of Icterus==

==Causes of Icterus==

===Pre-hepatic Jaundice===

===Pre-hepatic Jaundice===

Also sometimes called '''Haemolytic Icterus'''. This condition results from increased red blood cell destruction, overwhelming the capacity of the [[Liver - Anatomy & Physiology|liver]] to conjugate and excrete the bilirubin which is released into the plasma. The majority of the bilirubin is therefore '''unconjugated''' and, unlike the conjugated form, this cannot be excreted by the [[Urinary System Overview - Anatomy & Physiology|kidney]]. Possible causes of haemolysis and prehepatic jaundice include:

Also sometimes called '''Haemolytic Icterus'''. This condition results from increased red blood cell destruction, overwhelming the capacity of the [[Liver - Anatomy & Physiology|liver]] to conjugate and excrete the bilirubin which is released into the plasma. The majority of the bilirubin is therefore '''unconjugated''' and, unlike the conjugated form, this cannot be excreted by the [[Urinary System Overview - Anatomy & Physiology|kidney]]. Possible causes of haemolysis and prehepatic jaundice include:

*'''Haemolytic bacteria''', including ''[[Clostridium haemolyticum]]'' in cattle and [[Leptospira|'''Leptospires''']] in various species.

*'''Haemolytic bacteria''', including ''[[Clostridium haemolyticum]]'' in cattle and [[Leptospira|'''Leptospires''']] in various species.

*'''Haemolytic parasites''', including '''[[Babesia|Babesiosis]]''' in cattle and dogs and ''[[Feline Infectious Anaemia|Mycoplasma haemofelis]]'' in cats.

*'''Haemolytic parasites''', including '''[[Babesia|Babesiosis]]''' in cattle and dogs and ''[[Feline Infectious Anaemia|Mycoplasma haemofelis]]'' in cats.

*'''Immune reactions''' to red blood cells, including:

*'''Immune reactions''' to red blood cells, including:

**'''Neonatal isoerthryolysis''', resulting from the production of antibodies by the dam which are ingested by the neonate in colostrum and subsequently cause destruction of red blood cells.  Bilirubin is able to cross the immature blood brain barrier and cause direct damage to the neurones of the brain, a phenomenon called '''kernicterus'''.

**[[Neonatal Isoerythrolysis|'''Neonatal isoerthryolysis''']], resulting from the production of antibodies by the dam which are ingested by the neonate in colostrum and subsequently cause destruction of red blood cells.  Bilirubin is able to cross the immature blood brain barrier and cause direct damage to the neurones of the brain, a phenomenon called '''kernicterus'''.

**'''Autoimmune haemolytic anaemia''' or '''immune-mediated haemolytic anaemia'''.

**'''Autoimmune haemolytic anaemia''' or [[Immune Mediated Haemolytic Anaemia|'''immune-mediated haemolytic anaemia''']].

**Destruction of red blood cells of '''lambs fed with bovine colostrum'''.

**Destruction of red blood cells of '''lambs fed with bovine colostrum'''.

*'''Hypophosphataemia''', which may occur in cattle with '''post-parturient haemoglobinuria''', in animals with '''diabetic ketoacidosis''' (DKA) which are rapidly stabilised with insulin and in '''refeeding syndrome'''.

*'''Hypophosphataemia''', which may occur in cattle with '''post-parturient haemoglobinuria''', in animals with '''diabetic ketoacidosis''' (DKA) which are rapidly stabilised with insulin and in '''refeeding syndrome'''.

* Examples:

* Examples:

** [[Leptospira|''Leptospira icterohaemorrhagica'']] in the dog.

** [[Leptospira|''Leptospira icterohaemorrhagica'']] in the dog.

** Rift Valley fever virus.

** [[Rift Valley Fever|Rift Valley fever virus]].

** Some plant poisonings (''Lantana'')

** Some plant poisonings (''Lantana'')

** Some fungal infections ([[Mycotoxins|Aflatoxicosis]])

** Some fungal infections ([[Mycotoxins|Aflatoxicosis]])

===Post-hepatic Jaundice===

===Post-hepatic Jaundice===

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:

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.

**'''Gall bladder mucocoeles''' produce a kiwi sign on radiographs and may be a sequel to cystic mucinous hyperplasia of the gall bladder mucosa.

**'''Gall bladder mucoceles''' produce a kiwi sign on radiographs and may be a sequel to cystic mucinous hyperplasia of the gall bladder mucosa.

**'''Biliary neoplasia''', most commonly cholangiocellular cystadenoma (in cats) or carcinoma (in dogs).

**'''Biliary neoplasia''', most commonly cholangiocellular cystadenoma (in cats) or carcinoma (in dogs).

**Aberrent migration of '''intestinal parasites''', including ''[[Ascaris suum]]'' in pigs and ''[[Parascaris equorum]]'' in horses.  This occur particularly when worms have been treated with an anthelmintic that causes spasticity of the muscles.

**Aberrant migration of '''intestinal parasites''', including ''[[Ascaris suum]]'' in pigs and ''[[Parascaris equorum]]'' in horses.  This occur particularly when worms have been treated with an anthelmintic that causes spasticity of the muscles.

*'''Extraluminal obstructions''':

*'''Extraluminal obstructions''':

**[[Pancreatitis|'''Pancreatitis''']], '''pancreatic abcess''' or '''neoplasm'''

**[[Pancreatitis|'''Pancreatitis''']], '''pancreatic abscess''' or '''neoplasm'''

**[[Biliary Tract - Rupture|'''Biliary tract rupture''']]

**[[Biliary Tract Rupture|'''Biliary tract rupture''']]

**'''Pyloric''' or '''duodenal mass'''

**'''Pyloric''' or '''duodenal mass'''

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.

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.

 

 

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==References==   

==References==   

Gorman N (1998) '''Canine Medicine and Therapeutics''' ''Blackwell Sciences''

Gorman N (1998) '''Canine Medicine and Therapeutics''' ''Blackwell Sciences''

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