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==Description==
==Description==
[[Image:Oesophageal Stricture.png|thumb|right|300px|An oesophageal stricture observed by oesophagoscopy - Copyright David Walker 2009 RVC]]
[[Image:Oesophageal Stricture.png|thumb|right|300px|An oesophageal stricture observed by oesophagoscopy<br><small> Copyright David Walker 2009 RVC]]</small>
An oesophageal stricture is an abnormal circumferential narrowing of the oesophageal lumen secondary to severe [[Oesophagitis|oesophagitis]]. Deep injuries to the oesophageal wall heal by fibrosis which contracts over time to form the stricture. Animals may suffer from multiple strictures and the most common sites are within the '''distal high pressure zone''' (close to the lower oesophageal spincter), over the '''base of the heart''' and '''at the thoracic inlet'''. The oesophagus is narrower at these points and foreign bodies and refluxed ingesta are therefore more likely to accumulate at these locations. The most important causes of strictures include:
An oesophageal stricture is an abnormal circumferential narrowing of the oesophageal lumen secondary to severe [[Oesophagitis|oesophagitis]]. Deep injuries to the oesophageal wall heal by fibrosis which contracts over time to form the stricture. Animals may suffer from multiple strictures and the most common sites are within the '''distal high pressure zone''' (close to the lower oesophageal spincter), over the '''base of the heart''' and '''at the thoracic inlet'''. The oesophagus is narrower at these points and foreign bodies and refluxed ingesta are therefore more likely to accumulate at these locations. The most important causes of strictures include:
*'''Physical Injury'''
*'''Physical Injury'''
===Diagnostic Imaging===
===Diagnostic Imaging===
[[Image:Oesophageal Stricture Flouroscopy.png|thumb|right|300px|An oesophageal stricture observed by fluoroscopy in the region of the thoracic inlet - Copyright David Walker 2009 RVC]]
[[Image:Oesophageal Stricture Flouroscopy.png|thumb|right|300px|An oesophageal stricture observed by fluoroscopy in the region of the thoracic inlet <br><small> Copyright David Walker 2009 RVC]]</small>
Fibrosing strictures must be differentiated from [[Vascular Ring Anomalies|vascular ring anomalies]], [[Oesophagitis|oesophagitis]] and intraluminal and extraluminal masses. This can be done with plain and contrast radiography, endoscopy and ultrasonography.
Fibrosing strictures must be differentiated from [[Vascular Ring Anomalies|vascular ring anomalies]], [[Oesophagitis|oesophagitis]] and intraluminal and extraluminal masses. This can be done with plain and contrast radiography, endoscopy and ultrasonography.
'''Plain radiographs''' are usually unremarkable in animals with simple oesophageal strictures but oral administration of '''barium contrast medium''' may demonstrate:
'''Plain radiographs''' are usually unremarkable in animals with simple oesophageal strictures but oral administration of '''barium contrast medium''' may demonstrate '''segmental''' or '''diffuse narrowing''' of the oesophagus and '''oesphageal dilatation''' proximal to the site of the stricture.
'''Fluoroscopy''' can be used to great effect to observe the passage of a food bolus along the oesophagus and to define the sites of multiple strictures.
'''Fluoroscopy''' can be used to great effect to observe the passage of a food bolus along the oesophagus and to define the sites of multiple strictures.
===Surgical Management===
===Surgical Management===
Surgical intervention usually involves gradually stretching the site of the stricture until the luminal diameter returns to normal. Since flow increases as the fourth power of the radius (according to the law of LaPlace), even small increases in diameter can produce significant improvements in clinical signs. Multiple procedures (4-12) are usually required to achieve acceptable results. Two techniques are commonly used:
Surgical intervention usually involves gradually stretching the site of the stricture until the luminal diameter returns to normal. Since flow increases as the fourth power of the radius (according to the law of LaPlace), even small increases in diameter can produce significant improvements in clinical signs. Multiple procedures (4-12) are usually required to achieve acceptable results. Bougeinage and balloon catheters are the methods used most commonly.
'''Bougeinage''' involves the passage of conical metal rods of increasing size along the oesophagus but alternatively, a '''balloon catheter''' can be advanced along and oesophagus and inflated at the site of the stricture. This technique exerts pressure more evenly on the entire stricture, especially if it is not circumferential.
'''Surgical resection and anastomosis''' is not recommended because iatrogenic strictures may form at the anastomotic site. A simpler '''oesophagoplasty''' (similar to pyloroplasty for pyloric stenosis) may be performed, where the stricture is incised longitudinally and sutured transversely to increase the luminal diameter.
Anti-inflammatory doses of corticosteroids should again be used during these procedures to try to prevent re-stricturing.
Anti-inflammatory doses of corticosteroids should again be used during these procedures to try to prevent re-stricturing.
[[Category:Oesophagus_-_Pathology]]
[[Category:Oesophagus_-_Pathology]]
[[Category:To_Do_-_James]]
[[Category:To_Do_-_James]]
[[Category:To_Do_-_Review]]