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| | + | {{frontpage |
| | + | |pagetitle =Obstruction, Intestinal |
| | + | |pagebody = <div style="text-align: left; direction: ltr; margin-left: 1em;"> |
| | Intestinal obstruction can be the sequel to either mechanical or functional causes. Mechanical obstruction occurs due to physical blockage of the intestinal lumen whereas functional obstruction results from a decrease or inhibition of intestinal motility due to loss of smooth muscle contraction (Brown et. al, 2007). | | Intestinal obstruction can be the sequel to either mechanical or functional causes. Mechanical obstruction occurs due to physical blockage of the intestinal lumen whereas functional obstruction results from a decrease or inhibition of intestinal motility due to loss of smooth muscle contraction (Brown et. al, 2007). |
| − | ===Mechanical Obstruction=== | + | </div> |
| | + | |contenttitle =Content |
| | + | |contentbody =<big><b> |
| | | | |
| − | * Acute of chronic mechanical obstruction of the intestine can occur in all species.
| + | <categorytree mode=pages>Obstruction, Intestinal</categorytree> |
| − | ** Acute obstruction usually involves the upper or middle [[Small Intestine - Anatomy & Physiology|small intestine]]
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| − | ** Chronic obstruction typically occurs in the distal [[Small Intestine - Anatomy & Physiology|small intestine]] or [[Large Intestine - Anatomy & Physiology|large intestine]].
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| − | * Three main categories of causes of obstruciton:
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| − | ** Intraluminal
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| − | *** E.g. foreign bodies, food impaction.
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| − | ** Intramural
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| − | *** E.g. neoplasia
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| − | ** Extrinsic
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| − | *** E.g. adhesions, neoplasia and prostate enlargement.
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| | | | |
| − | ====Intraluminal Obstruction==== | + | </b></big> |
| | + | |logo =path-logo.png |
| | + | }} |
| | | | |
| − | =====Foreign Bodies=====
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| | | | |
| − | * Foreign bodies of all types can be found in the intestines.
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| − | * While some may pass through posing no problems, others can cause acute obstruction,
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| − | * Quite common in dogs
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| − | ** Rare in other species - tend to lodge in the oesophagus or in one of the ruminant [[Stomach and Abomasum - Anatomy & Physiology|stomachs]].)
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| − | ** Enteroliths can be seen in horses greater than 4 years of age.
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| − | *** Are stones consisting of magnesium ammonium phosphate around a central nidus (often a metallic foreign body)
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| − | *** Typically lodge at the pelvic flexure or the transverse [[Colon - Anatomy & Physiology|colon]].
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| − | * '''Clinical'''
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| − | ** Obstruction at pylorus produces repeated [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|vomiting]].
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| − | ** Obstrustion lower down gives less dramatic effect.
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| − | *** Is still a problem if in the middle of the [[Small Intestine - Anatomy & Physiology|small intestine]]s.
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| − | *** May be vague signs; some [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|vomiting]] and off food.
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| − | * '''Diagnosis'''
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| − | ** May not show up well radiographically (unless radio-opaque) for several days.
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| − | *** May also be objects that are semi solid or soft, e.g.
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| − | **** String
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| − | **** Plastic bags
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| − | **** Stringy things, like pieces of material- particularly in puppies.
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| − | ** Make all of intestines have knotted appearance.
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| − | ** May be seen in horses with baler twine.
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| − | * '''Pathogenesis'''
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| − | ** Smooth, round objects, such as golf balls, lodge especially near the pylorus or lower down.
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| − | ** Occasionally in cattle (piece of rope or piece of tarpaulin) produces a tangled mass in [[The Rumen - Anatomy & Physiology|rumen]].
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| − | ** Cause pressure necrosis and eventually perforation.
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| − | ** Foreign bodies can also be chronic, remaining for long periods of time without causing disturbance.
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| − |
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| − | =====Impaction=====
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| − |
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| − | * Impaction of the [[Colon - Anatomy & Physiology|colon]] can occur in all species.
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| − | ** Dog and cat - main cause is dehydrated faecal material.
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| − | ** Horse - faeces, digesta, sand, or fibrous material can all contribute.
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| − | *** There are certain predisposing factors:
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| − | **** Poor dentition
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| − | **** Water deprivation
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| − | **** A high roughage diet
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| − | **** General debility.
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| − | *Antihelminthic administration or large parasite burdens can also lead to impaction.
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| − |
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| − | ====Extrinsic Obstruction====
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| − |
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| − | * Obstruction of the intestine due to external factors such as tumours, abscesses, and fibrous adhesions is a common occurrence.
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| − |
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| − | =====Inflammatory Adhesions=====
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| − | [[Image:colon_adhesions_horse.jpg|thumb|right|150px|colonic adhesions in the horse (Courtesy of Elspeth Milne)]]
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| − |
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| − | * Arise following gut perforation, peritonitis or surgery.
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| − | * Consist of fibrous tissue bands that may:
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| − | ** Restrict intestinal motility
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| − | ** Cause kinks in the mesentery.
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| − |
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| − | =====Prostatic Enlargement=====
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| − |
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| − | * In the dog
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| − | * Can lead to compression of the [[Rectum - Anatomy & Physiology|rectum]]
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| − |
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| − | =====Neoplasia=====
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| − |
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| − | * Neoplasi in structures adjacent to the intestines can spread and cause external compression.
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| − | * Pancreatic tumours in particular can extend and impinge on the [[Duodenum - Anatomy & Physiology|duodenum]].
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| − | * Pedicles of tumours such as lipomas in horses can become wound in loops of intestine leading to obstruction and possible strangulation.
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| − | [[Image:Pedunc_lipoma_closeup.jpg|thumb|right|150px|Closeup of a pedunculated lipoma (Courtesy of Elspeth Milne)]]
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| − | * '''Clinical'''
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| − | ** Occasional [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|vomiting]] and ntermittent [[Intestine Diarrhoea - Pathology|diarrhoea]] over several weeks.
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| − | * '''Pathogenesis'''
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| − | ** Seen occasionally in cat (rarer in dog)
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| − | ** Usually towards end of intestines
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| − | *** E.g. at the ileocaecocolic valve.
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| − | ** Gut proximal to tumour becomes thickened due to hypertrophy of smooth muscle as a result of trying to force ingesta past progessively narrowing lumen.
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| − | ** Produces "hose pipe intestine".
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| − | ** Seen with carcinoma, lymphoma, leiomyoma and other tumours.
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| − |
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| − | ===Functional Obstruction===
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| − |
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| − | ====Paralytic Ileus====
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| − |
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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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| − |
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| − | =====Causes=====
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| − |
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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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| − |
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| − | =====Pathology=====
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| − |
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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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| − |
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| − | =====Pathogenesis=====
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| − |
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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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| − |
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| − | ====Dysautonomia====
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| − |
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| − | * Most notably affects horses and cats.
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| − |
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| − | =====Equine dysautonomia, or grass sickness=====
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| − |
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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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| − |
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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]].
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| | [[Category:Intestine - Physical Disturbances]] | | [[Category:Intestine - Physical Disturbances]] |
