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See also: '''[[Biliary Tract Rupture]]'''

| See also:

| '''[[Biliary Tract - Rupture]]'''

==Description==

==Introduction==

The biliary tract comprises the [[Gall Bladder - Anatomy & Physiology|gall bladder]], hepatic duct, common bile duct and the duodenal papilla onto which it opens.  If any part of this tract is obstructed, the normal flow of [[Bile Formation|bile]] is interrupted resulting in [[Cholestasis, Molecular Pathogenesis|cholestasis]] and [[Icterus#Post-hepatic Jaundice|post-hepatic jaundice]].  If the obstruction is not relieved, the biliary tract may [[Biliary Tract - Rupture|rupture]] to produce a chemical [[Peritonitis|bile peritonitis]].

The biliary tract comprises the [[Gall Bladder - Anatomy & Physiology|gall bladder]], hepatic duct, common bile duct and the duodenal papilla onto which it opens.  If any part of this tract is obstructed, the normal flow of [[Bile Formation|bile]] is interrupted resulting in [[Cholestasis, Molecular Pathogenesis|cholestasis]] and [[Icterus#Post-hepatic Jaundice|post-hepatic jaundice]].  If the obstruction is not relieved, the biliary tract may [[Biliary Tract Rupture|rupture]] to produce a chemical [[Peritonitis|bile peritonitis]].

The causes of biliary tract obstruction may be '''intraluminal''' or '''extraluminal''':

The causes of biliary tract obstruction may be '''intraluminal''' or '''extraluminal''':

*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.

<u>Intraluminal obstructions:</u>

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

*'''[[Cholelithiasis|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.

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

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

**'''Aberrant migration of intestinal helminths''' may cause an obstruction if they enter the common bile duct.  This has been reported with ''[[Ascaris suum]]'' in pigs and ''[[Parascaris equorum]]'' in horses and it may occur after these animals have been treated with an anthelmintic that causes spasticity of the parasite muscles.

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

*Extraluminal obstructions:

*'''Aberrant migration of intestinal helminths''' may cause an obstruction if they enter the common bile duct.  This has been reported with ''[[Ascaris suum]]'' in pigs and ''[[Parascaris equorum]]'' in horses and it may occur after these animals have been treated with an anthelmintic that causes spasticity of the parasite muscles.

**[[Pancreatitis - Dog and Cat|'''Pancreatitis''']] is the most common cause of obstruction in dogs.  '''Pancreatic abcesses''' or '''neoplasia''' may also obstruct the flow of bile.

<u>Extraluminal obstructions:</u>

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

*[[Pancreatitis|'''Pancreatitis''']] is the most common cause of obstruction in dogs.  '''Pancreatic abcesses''' or '''neoplasia''' may also obstruct the flow of bile.

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

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

**'''Diaphragmatic rupture''' with herniation of parts of the liver may result in exertion of pressure on the biliary tract.

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

**'''Biliary pseudocysts''' are a rare cause of obstruction.

*'''Diaphragmatic rupture''' with herniation of parts of the liver may result in exertion of pressure on the biliary tract.

*'''Biliary pseudocysts''' are a rare cause of obstruction.

==Diagnosis==

==Diagnosis==

The signs of biliary obstruction relate to the failure of bile to move into the small intestine and to the reduction in function of the hepatic monocyte-phagocyte system.

The signs of biliary obstruction relate to the failure of bile to move into the small intestine and to the reduction in function of the hepatic monocyte-phagocyte system.

===Clinical Signs===

===Clinical Signs===

'''[[Vomiting]]''' and '''anorexia''' are the most common signs of biliary obstruction.

'''[[Vomiting]]''' and '''anorexia''' are the most common signs of biliary obstruction.

==Prognosis==

==Prognosis==

The prognosis depends on the cause of the obstruction but affected animals are often very ill.   

The prognosis depends on the cause of the obstruction but affected animals are often very ill.   

==References==

==References==

* Fossum, T. W. et. al. (2007) '''Small Animal Surgery (Third Edition)''' ''Mosby Elsevier''

* Fossum, T. W. et. al. (2007) '''Small Animal Surgery (Third Edition)''' ''Mosby Elsevier''

[[Category:Gall_Bladder_and_Tract_-_Pathology]]

[[Category:Gall_Bladder_and_Tract_-_Pathology]]

[[Category:To_Do_-_James]]

[[Category:Gall Bladder and Tract Diseases - Dog]][[Category:Gall Bladder and Tract Diseases - Cat]][[Category:Biliary Diseases - Cattle]][[Category:Biliary Diseases - Pig]]

[[Category:Dog]][[Category:Cat]][[Category:Horse]][[Category:Cattle]][[Category:Pig]]

[[Category:Expert_Review - Small Animal]]

[[Category:To_Do_-_Review]]

[[Category:Liver Diseases - Horse]]