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Also known as: '''''Extra-hepatic Biliary Tract Obstruction — EHBO
Also known as: '''''Extra-hepatic Biliary Tract Obstruction — EHBO
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''':
<u>Intraluminal obstructions:</u>
<u>Intraluminal obstructions:</u>
*'''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.
*'''[[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.
*'''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 mucocoeles''' 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).
*'''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.
*'''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.
<u>Extraluminal obstructions:</u>
<u>Extraluminal obstructions:</u>
*[[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.
*[[Pancreatitis|'''Pancreatitis''']] is the most common cause of obstruction in dogs. '''Pancreatic abcesses''' or '''neoplasia''' may also obstruct the flow of bile.
*[[Biliary Tract - Rupture|'''Biliary tract rupture''']]
*[[Biliary Tract Rupture|'''Biliary tract rupture''']]
*'''Pyloric''' or '''duodenal mass'''
*'''Pyloric''' or '''duodenal mass'''
*'''Diaphragmatic rupture''' with herniation of parts of the liver may result in exertion of pressure on the biliary tract.
*'''Diaphragmatic rupture''' with herniation of parts of the liver may result in exertion of pressure on the biliary tract.
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.
==Literature Search==
{{Learning
[[File:CABI logo.jpg|left|90px]]
|Vetstream = [https://www.vetstream.com/canis/Content/Freeform/fre60060.asp Gall bladder disease: overview]
|literature search =
[http://www.cabdirect.org/search.html?q=%28title%3A%28%22biliary+tract%22%29+AND+ab%3A%28obstruction%29%29+OR+title%3A%28EHBO%29 Biliary tract obstruction publications]
[http://www.cabdirect.org/search.html?q=%28title%3A%28%22biliary+tract%22%29+AND+ab%3A%28obstruction%29%29+OR+title%3A%28EHBO%29 Biliary tract obstruction publications]
}}
==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''
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[[Category:Gall_Bladder_and_Tract_-_Pathology]]
[[Category:Gall_Bladder_and_Tract_-_Pathology]]
[[Category:Gall Bladder and Tract Diseases - Dog]][[Category:Gall Bladder and Tract Diseases - Cat]][[Category:Biliary Diseases - Cattle]][[Category:Biliary Diseases - Pig]]
[[Category:Gall Bladder and Tract Diseases - Dog]][[Category:Gall Bladder and Tract Diseases - Cat]][[Category:Biliary Diseases - Cattle]][[Category:Pig]]
[[Category:Expert_Review - Small Animal]]
[[Category:Expert_Review]]
[[Category:Liver Diseases - Horse]]
[[Category:Liver Diseases - Horse]]