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| − | {{toplink
| + | #REDIRECT[[:Category:Oesophagus - Pathology]] |
| − | |backcolour =BCED91
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| − | |linkpage =Alimentary System - Pathology
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| − | |linktext =Alimentary System
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| − | |maplink = Alimentary System (Content Map) - Pathology
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| − | |pagetype =Pathology
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| − | }}
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| − | <br>
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| − | ==Introduction==
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| − | *The [[Oesophagus - Anatomy & Physiology|oesophagus]] is the part of alimentary tract that tends to go wrong least often.
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| − | ==Functional Anatomy==
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| − | *The [[Oesophagus - Anatomy & Physiology|oesophagus]] is a fibromuscular tube, lined by stratified squamous epithelium and lubricated by mucus, salivary, nasal and bronchial secretions, which acts to transport ingesta from the [[Pharynx - Anatomy & Physiology|pharynx]] to the [[Forestomach - Anatomy & Physiology|stomach]].
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| − | *Failure of [[Oesophagus - Anatomy & Physiology|oesophageal]] function results in obstruction and in failure of ingesta to pass to the [[Forestomach - Anatomy & Physiology|stomach]].
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| − | *In the bovine there may also be failure of [[Eructation - Anatomy & Physiology|eructation]] and [[tympany]] may develop.
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| − | | |
| − | ==Defence Mechanisms==
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| − | *The [[Oesophagus - Anatomy & Physiology|oesophagus]] has '''no serosa''' and is covered by the fibrous tissue of the neck and mediastinum, from which it derives its blood supply.
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| − | *Consequently, infection spreads easily and healing is more difficult.
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| − | *[[Oesophagus - Anatomy & Physiology|Oesophageal]] disease is therefore difficult to treat and is consequently very serious.
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| − | | |
| − | ==Developmental Pathology==
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| − | ===Congenital Achalasia - Megaoesophagus===
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| − | [[Image:Megaoes.gif|left|thumb|125px|<small><center>Megaoesophagus (Courtesy of Alun Williams (RVC))</center></small>]]
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| − | *This condition has been termed achalasia but this implies (in man) a cardiac sphincter defect, which is not found in the dog.
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| − | *A functional rather than a [[#Traumatic Pathology|physical blockage]]
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| − | | |
| − | *Inherited disorder in several breeds:
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| − | **Autosomal recessive in Fox Terrier.
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| − | **Also in Miniature Schnauzer, Great Dane, German Shepherds and others.
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| − | **Also in Siamese cats.
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| − | | |
| − | ====Clinical====
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| − | *See at approx. 6-7 months of age when growing quickly.
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| − | *Eats food, [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|vomits]], eats again and [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|vomits]] again because [[Oesophagus - Anatomy & Physiology|oesophagus]] has no tone to it.
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| − | *[[Oesophagus - Anatomy & Physiology|Oesophagus]] may become extremely dilated producing a megaoesophagus.
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| − | *Can affect the whole length of [[Oesophagus - Anatomy & Physiology|oesophagus]].
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| − | | |
| − | ====Pathogenesis====
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| − | *Appears to be due to due to delay in maturation of [[Oesophagus - Anatomy & Physiology|oesophageal]] innervation, either:
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| − | **in upper motor neurones of central swallowing centre or
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| − | **in the afferent sensory arm of the reflex involved with [http://en.wikipedia.org/wiki/Peristalsis| peristalsis].
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| − | | |
| − | *If dog eats from raised bowel may be satisfactory as food goes down by gravity.
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| − | *Once in [[Forestomach - Anatomy & Physiology|stomach]] it is passed on normally.
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| − | | |
| − | ===Megoesophagus Secondary to Dextra-Aorta===
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| − | [[Image:Praa.gif|right|thumb|125px|<small><center>Dextra-aorta (Courtesy of Alun Williams (RVC))</center></small>]]
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| − | *Vascular rings are congenital abnormalities of the aortic arch system which interfere with [[Oesophagus - Anatomy & Physiology|oesophageal]] function. Normally, the aortic arch, pulmonary artery and ductus arteriosus (ligamentum arteriosum) all lie on the left side of the [[Oesophagus - Anatomy & Physiology|oesophagus]].
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| − | *However, when there is anomalous development of the aortic arch, for example in the [[right-sided arch]], the [[Oesophagus - Anatomy & Physiology|oesophagus]] becomes enclosed within a ring formed by the '''heart base''', '''aorta''', '''ductus arteriosus''' and '''pulmonary artery'''.
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| − | *The compression and stricture produced by the “ring” presents passage of solid food beyond the heart base and food accumulates rostral (cranial) to the obstruction, resulting in dilatation or megaoesophagus.
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| − | *In most cases food is eventually regurgitated undigested.
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| − | *The condition is seen in pups just after weaning and if these are presented for treatment before severe dilatation occurs, then surgical correction of the ring (if possible) offers a good prognosis.
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| − | | |
| − | ==Erosive & Ulcerative Pathology==
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| − | ==Vesicular Pathology==
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| − | ==Neutrophilic Inflammation==
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| − | ==Granulomatous and pyogranulomatous Inflammation==
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| − | ==Eosinophilic Inflammation==
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| − | ==Necrotizing Inflammation==
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| − | ==Lymphocytic and plasmacytic Inflammation==
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| − | ==Immune Mediated Pathology==
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| − | ===Autoimmune===
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| − | ====Myasthenia Gravis====
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| − | *Animals develop antibodies to nicotinic acetylcholine receptors.
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| − | *Results in generalised muscle weakness and or megaoesophagus.
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| − | | |
| − | ====Key-Gaskell syndrome====
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| − | *Autonomic polyganglioneuropathy in cats
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| − | *Abnormal function of the sympathetic and parasympathetic system.
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| − | *Whole autonomic system involved – affected animals usually die.
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| − | **Similar to [[Intestines - physical disturbances#Equine dysautonomia, or grass sickness|grass sickness]] in horses.
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| − | | |
| − | =====Clinical=====
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| − | *Cats show:
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| − | **Mega-oesophagus
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| − | **Dilated pupils
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| − | **Whole gut is involved (very little peristalsis)
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| − | **Constipation.
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| − | | |
| − | *Generalised autonomic effects:
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| − | **Reduced salivation
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| − | **Reduced lachrymation
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| − | **Bradycardia
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| − | **Constipation
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| − | **Pupillary dilatation
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| − | | |
| − | =====Pathology=====
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| − | *Histologically there is marked reduction in the number of neurones in all autonomic ganglia in the ventral horn of all levels of spinal cord accompanied by proliferation of non-neuronal cells.
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| − | *Similar changes in brain stem nuclei of cranial nerves.
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| − | =====Pathogenesis=====
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| − | *Acquired disease - outbreaks occurred in the past, now only occasionally seen but seems to be getting more common again.
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| − | *Possibly toxic cause.
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| − | *Possibly in dry food or in vaccine?
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| − | *Agent not really known, but produces general damage to autonomic nervous system.
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| − | ===Hypersensitivity===
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| − | ==Proliferative Pathology==
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| − | ===Hyperplastic===
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| − | ===Papular===
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| − | ====Bovine Papular Stomatitis====
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| − | [[Image:BPSOES.gif|right|thumb|125px|<small><center>Oesophageal lesions of BPS (Courtesy of Alun Williams (RVC))</center></small>]]
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| − | Lesions of [[Cavity & Gingiva - Pathology#Bovine Papular stomatitis|Bovine Papular Stomatitis]] may also be found in the [[Oesophagus - Anatomy & Physiology|oesophagus]].
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| − | ===Neoplastic===
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| − | ====Upper Alimentary Tract Carcinoma Complex====
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| − | | |
| − | =====Aetiology=====
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| − | *The most important [[Oesophagus - Anatomy & Physiology|oesophageal]] neoplasm is squamous cell carcinoma in the cow.
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| − | *This tumour is seen as part of a more general syndrome of upper alimentary tract neoplasia in adult cattle grazing rough pasture on which the '''bracken fern''' (Pteridium aquilinum) is present.
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| − | *The syndrome is seen in various part of the world including the Western Highlands of Scotland, Brazil and Kenya.
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| − | *In affected animals, squamous carcinomas may be present in the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]], [[Oesophagus - Anatomy & Physiology|oesophagus]] and [[The Rumen|rumen]] and there may also be [[intestinal adenocarcinomas]] and bladder tumours, or the condition known as [[enzootic bovine haematuria]].
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| − | | |
| − | =====Pathogenesis=====
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| − | *Experimentally, the feeding of bracken to laboratory animals will result in alimentary and [[Bladder - Anatomy & Physiology|bladder]] tumours.
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| − | *However, in many naturally-occurring cases of upper alimentary carcinoma in cattle there are coexisting viral papillomata, some of which show malignant change.
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| − | *The relationship between the ingestion of bracken and the presence of virus in the aetiology of the malignancies is currently the subject of intensive investigations.
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| − | *It may be that both are involved in the carcinogenesis.
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| − | | |
| − | =====Macroscopically=====
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| − | *These upper alimentary squamous carcinomas are most often seen as:
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| − | **large
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| − | **fungating
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| − | **often superficially-necrotic
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| − | **protruding into the lumen of the [[Alimentary - Anatomy & Physiology|alimentary tract]];
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| − | *There is often a marked scirrhous reaction.
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| − | *The tumours are locally aggressive and may permeate local lymphatics and metastasise to local lymph nodes.
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| − | | |
| − | =====Microscopically=====
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| − | The tumour consists of cords or groups of squamous cells, which may form keratin.
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| − | Individual or multiple papillomata may be found in association with the carcinomata.
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| − | *The presence of the tumours interferes with normal alimentary function
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| − | **there may be difficulty in chewing and [[Deglutition|swallowing]] or in cudding and [[Eructation - Anatomy & Physiology|eructation]].
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| − | | |
| − | ====Squamous Cell Carcinoma of Other Species====
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| − | *Squamous cell carcinomas of the [[Oesophagus - Anatomy & Physiology|oesophagus]] are occasionally seen in other species, notably in the cat, where the tumour tends to infiltrate around the oesophageal wall resulting in a “'''ring carcinoma'''”.
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| − | *The affected cat has progressive difficulty in eating and [[Deglutition|swallowing]].
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| − | ==Degenerative Pathology==
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| − | ===Acquired megaoesophagus===
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| − | *Occurs spontaneously in adult in any disorder that disrupts normal reflex involved in swallowing either peripheral or central.
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| − | *These can include:
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| − | **Viral encephalitides
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| − | **Peripheral neuropathies
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| − | ***Degeneration or inactivity of local myenteric nerve plexuses (Auerbach’s plexuses),
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| − | ***or to lesions in the vagus nerve or the central nucleus in the medulla of the brain which supply the [[Oesophagus - Anatomy & Physiology|oesophagus]].
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| − | **Poisonings such as:
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| − | ***Lead
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| − | ***Tetanus
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| − | ***Botulism
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| − | **Myopathies.
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| − | *The result is the presence of a hypotonic [[Oesophagus - Anatomy & Physiology|oesophagus]] in which food accumulates causing distension
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| − | *Usually the thoracic oesophagus from the thoracic inlet to the diaphragm is affected and grossly the [[Oesophagus - Anatomy & Physiology|oesophagus]] is dilated, thin-walled and hypotonic.
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| − | ==Metabolic Pathology==
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| − | ==Nutritional Pathology==
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| − | ==Traumatic Pathology==
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| − | ===Impaction===
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| − | {| style="color:darkblue;background-color:#ffffcc;" cellpadding="10" cellspacing="0" border="1"
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| − | |'''Upper Block'''
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| − | |'''Lower Block'''
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| − | |-
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| − | | Acute vomiting
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| − | | Gradual intestinal distention
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| − | |-
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| − | | Dehydration
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| − | | Mucosal destruction
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| − | |-
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| − | | Alkalosis
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| − | | Toxaemia
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| − | |-
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| − | | Pre-renal azotaemia
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| − | | Peritonitis
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| − | |}
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| − | *Commonly in cattle, horses and dogs.
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| − | *The most common sites of obstruction are the '''thoracic inlet''', '''the base of the heart''', and the '''hiatus oesophagus''' of the diaphragm, i.e.: the narrowest points.
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| − | | |
| − | ====Clinical Signs====
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| − | ====Horse====
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| − | *With foods that expand in [[Oesophagus - Anatomy & Physiology|oesophagus]] such as haylage etc.
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| − | *Also seen with whole apples.
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| − | | |
| − | ====Cattle====
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| − | [[Image:Bovimpaction.gif|right|thumb|125px|<small><center>Impaction of a bovine oesophagus (Courtesy of Alun Williams (RVC))</center></small>]]
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| − | *May eat a spherical object that obstructs the [[Oesophagus - Anatomy & Physiology|oesophagus]] mostly in anterior 1/3rd of [[Oesophagus - Anatomy & Physiology|oesophagus]] and can often be palpated in live animal.
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| − | *Potatoes can be a cheap source of feed and if fed whole can become stuck in [[Oesophagus - Anatomy & Physiology|oesophagus]].
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| − | *If obstruction occurs further down can be difficult to diagnose and remove.
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| − | *Cattle develop bloat when [[Oesophagus - Anatomy & Physiology|oesophagus]] obstructed.
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| − | *Apples fairly easily to dislodge.
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| − | ====Dog====
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| − | *Usually with small bones
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| − | *Animals that feel protective of feed may gulp food down quickly, particularly if given small chops / knuckle bones.
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| − | *Knobbly shape may make bone lodge in [[Oesophagus - Anatomy & Physiology|oesophagus]], particularly just anterior to heart.
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| − | *Very difficult to dislodge (because of shape).
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| − | *Pressure necrosis occurs very quickly around it and can erode through [[Oesophagus - Anatomy & Physiology|oesophagus]] within about 24 hours.
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| − | *Small bone may also lodge in [[Duodenum - Anatomy & Physiology|duodenum]] if they pass through the [[Forestomach - Anatomy & Physiology|stomach]].
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| − | | |
| − | ===Rupture===
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| − | *Perforation may occur with sharp foreign bodies. This may lead to [[cellulitis]] or [[pleurisy]] and other complications.
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| − | *Rupture of the [[Oesophagus - Anatomy & Physiology|oesophagus]] admits pathogenic organisms to the mediastinum and fascial planes of the neck. Both are composed of loose connective tissue and communicate with each other.
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| − | *Infection spreads rapidly as a cellulitis, aided possibly by peristalsis and pulsation of the carotid arteries, and soon leads to pleurisy.
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| − | *'''Rupture is almost always fatal.'''
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| − | ==Vascular Pathology==
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| − | ==(Other)==
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| − | ==Learning Tools==
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| − | [[Alimentary Flashcards - Pathology#Oesophagus Flashcards|Oesophagus Flashcards]]
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