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===Functional Obstruction===
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===[[:Category:Intestine - Functional Obstruction]]===
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====Paralytic Ileus====
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* A common condition.
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* Occurs following trauma or abdominal surgery. 
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* Stasis of gut flow due to failure of [http://en.wikipedia.org/wiki/Peristalsis| peristalsis].
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** Leads to distension with gas and fluid, as well as a flaccid intestinal wall. 
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=====Causes=====
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* Anything which stops peristalsis, e.g.
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** Damage to nerve supply to intestine (autonomic nervous system)
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** Pain
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** Abnormal metabolism
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** Toxaemia
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** Electrolyte imbalance such as hypocalcaemia, hypomagnesaemia, and hypokalaemia.
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* Also in
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** Diabetes mellitus
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** Uraemia
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** Tetanus
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** Lead poisoning.
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=====Pathology=====
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* loss of smooth muscle tone leads to a flaccid bowel.
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* Bowel is distended with fluid. 
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=====Pathogenesis=====
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* Intestine susceptible to neurogenic damage during an operation. 
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* Peristalsis fades away over a few days producing paralytic (adynamic) ileus.
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* Particularly occurs if bowel handled roughly, or if serosa gets cold and dry at surgery. 
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* Very difficult to start peristalsis again but will sometimes respond to pharmacological or electrical stimulation.
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* The horse is very susceptible, and the dog is somewhat suscpeitble.
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====Dysautonomia====
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* Most notably affects horses and cats.
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=====Equine dysautonomia, or grass sickness=====
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* Most prevalent  in the UK and western Europe.
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** Common in wetter areas, e.g. the South West.
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* Seen in horses out at pasture in late summer and autumn.
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* Usually affects young adults.
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** 6-7 years old.
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* '''Clinical'''
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** Acute oneset:
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*** Muscular tremors
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*** Abdominal pain
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*** Does not eat
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*** Constipation
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*** Become severly tympanic in acute cases
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*** Dull and restless
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*** Avoid swallowing
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*** Salivate excessively
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** Degenerative lesions are seen in the autonomic nerve ganglia, including enteric plexuses
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** May either:
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*** Progress rapidly to death
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*** Take a slower clinical course.
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**** Eat a bit, but food drops out of mouth
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**** Go on to die slowly.
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** Some horses recover
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*** This is very unlikely, and the condition is usually fatal. 
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** Clinically difficult to diagnose - signs are confined to the gut.
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*** Easy to diagnose on post mortem
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* '''Pathology'''
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** [[Forestomach - Anatomy & Physiology|Stomach]] and [[Small Intestine - Anatomy & Physiology|small intestine]] large amounts of contain watery yellow fluid.
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*** There is an abrupt change in the [[Large Intestine - Anatomy & Physiology|large intestine]], where no fluid is present.
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**** [[Large Intestine - Anatomy & Physiology|large intestine]] has very dry mucoid contents.
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* '''Pathogenesis'''
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** Due to functional obstruction at ileocaecal valve and a degree of paralytic ileus of the [[Small Intestine - Anatomy & Physiology|small intestine]].
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** The exact cause is unknown, but a type of bacterial or fungal toxin which may damage autonomic nervous system ganglia may be involved.
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*** ''[[Clostridium botulinum]]'' is thought to be involved. 
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* A similar condition seen in hares
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** Certain yeares almost seem to have outbreaks.
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* Certain pastures at certain times of year produce grass sickness quite often.
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** A definitive diagnosis must be made -  if the condition is due to the grazing we need to know.
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*** E.g. if on livery or stud grazing, may put people off going there.
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* 'Diagnosis''' 
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** At post mortem look for degenerative changes in coeliaco-mesenteric ganglia -  need to examine histologically. 
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*** Ganglia are peanut sized and found in perirenal fat between adrenal gland and the aorta.
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=====Feline dysautonomia, or Key-Gaskell Syndrome=====
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[[Image:Ba 250 07.jpg|thumb|right|Histological section of degenerate neuron in feline dysautonomia(Courtesy of Susan Rhind)]]
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* Occurs mostly in the UK and continental Europe. 
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* Is also of unknown aetiology. Suggested causative factors include:
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** Environmental toxins
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** Infectious agents
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** Botulinum toxins .
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* Clinical signs:
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** Anorexia
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** Depression
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** Bradycardia
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** Decreased lacrimation,
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** Altered pupillary dilataion,
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** [[Megaoesophagus]]
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** Constipation. 
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* Degenerative lesions of autonomic nerve ganglia can be seen.
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* Also occurs in the [[Key-Gaskell Syndrome|oesophagus]].
   
[[Category:Intestine - Physical Disturbances]]
 
[[Category:Intestine - Physical Disturbances]]
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