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**Ingestion of [[Oesophageal Foreign Body|'''foreign bodies''']] which lodge in the oesophagus.
**Ingestion of [[Oesophageal Foreign Body|'''foreign bodies''']] which lodge in the oesophagus.
**Passage of nasogastric or pharyngostomy '''feeding tubes''' or of large '''endoscopes'''.
**Passage of nasogastric or pharyngostomy '''feeding tubes''' or of large '''endoscopes'''.
**Erosion of the oesophageal wall by '''neoplasia''' or '''abscesses'''.
**Erosion of the oesophageal wall or extraluminal compression by '''neoplasia''' or '''abscesses'''.
**'''Surgical wounds''' to the oesophagus that heal with a fibrous component.
**'''Surgical wounds''' to the oesophagus that heal with a fibrous component.
*'''Chemical Injury'''
*'''Chemical Injury'''
===Diagnostic Imaging===
===Diagnostic Imaging===
Fibrosing strictures must be differentiated from [[Vascular Ring Anomalies|vascular ring anomalies]], [[Oesophagitis|oesophagitis]], intraluminal and extraluminal masses. This can be done with survey 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:
*Segmental or diffuse narrowing of the oesophagus
*'''Segmental''' or '''diffuse narrowing''' of the oesophagus.
*Oesphageal dilatation proximal to the site of the stricture
*'''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.
Ultrasonography is not usually useful in diagnosing small benign strictures but may visualise those caused by mass compression.
'''Ultrasonography''' is not usually useful in diagnosing simple strictures but may visualise those caused by extraluminal compression by mediastinal neoplasia or abscesses.
Oesophagoscopy is used for a definitive diagnosis. It should be used to confirm the site and severity of the stricture and also to exclude the presence of an intraluminal mass.
'''Oesophagoscopy''' may be used to obtain a definitive diagnosis but it requires a general anaesthetic (which may have been the cause of the problem) and, if a large endoscope is passed, this may cause further physical damage to the oesophagus. Also, endoscopy is not sensitive for the diagnosis of multiple strictures if it is unable to pass through the most proximal. It can also be used to identify and biopsy any intraluminal masses.
==Treatment==
==Treatment==
===Medical Management===
The suspected cause (ie.[[Oesophagitis|oesophagitis]]) should be corrected initially. Components of medical management include:
*'''Withdrawal of oral food for 2-3 days''' as standard but, if the inflammation is severe or rupture has occurred, a '''gastrostomy tube''' may be required.
*'''Oral sucralfate suspension''' is thought to bind to the base of any ulcers, to stimulate epithelial repair and to neutralise any refluxed gastric juices.
*'''Gastric acid secretory inhibitors''' (e.g. ranitidine, omeprazole) can be useful in cases of gastro-oesophageal reflux.
*'''Metaclopramide''', a promotility drug that increases the tone of the lower oesophageal sphincter, may also be used to manage gastro-oesophageal reflux but not if oesophageal motility is thought to be impaired (i.e., if megaoesophagus is present).
*'''Broad spectrum intra-venous bactericidal antibiotics''' may be required in animals with severe oesophagitis or aspiration pneumonia. Coupage and nebulisation may be useful adjunctive treatments for aspiration pneumonia and it may be necessary to provide oxygen to dyspnoeic animals.
*'''Analgesia''' should be provided to encourage animals to eat after 2-3 days.
*Anti-inflammatory doses of [[Steroids|corticosteroids]] (such as prednisolone) may be used to prevent fibrosis and further stricture formation in acute injuries but caution should be exercised if the animal has concurrent aspiration pneumonia.
===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:
*'''Bougeinage''' involves the passage of conical metal rods of increasing size along the oesophagus
*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.
*[[Gastroprotective Drugs]]
*'''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.
**Gastric acid secretory inhibitors (cimetidine, ranitidine, omeprazole)
*Surgical resection is not recommended because iatrogenic strictures at the anastomotic site are possible.
==Prognosis==
==Prognosis==
The shorter the length of oesophagus involved and the quicker the corrective procedure is performed the better the prognosis.
The shorter the length of oesophagus involved and the quicker the corrective procedure is performed, the better the prognosis. Animals with large, mature strictures and those with continued oesophagitis have a guarded prognosis and long-term gastrostomy tubes may be required in these cases.
Animals with large, mature strictures and those with continued oesophagitis have a guarded prognosis. Long term gastrostomy tubes may be required in some cases.
==References==
==References==