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Category:Intestine - Mechanical Obstruction (view source)
Revision as of 12:29, 31 May 2010
, 12:29, 31 May 2010Created page with '* Acute of chronic mechanical obstruction of the intestine can occur in all species. ** Acute obstruction usually involves the upper or middle [[Small Intestine - Anatomy & Physi…'
* Acute of chronic mechanical obstruction of the intestine can occur in all species.
** Acute obstruction usually involves the upper or middle [[Small Intestine - Anatomy & Physiology|small intestine]]
** Chronic obstruction typically occurs in the distal [[Small Intestine - Anatomy & Physiology|small intestine]] or [[Large Intestine - Anatomy & Physiology|large intestine]].
* Three main categories of causes of obstruciton:
** Intraluminal
*** E.g. foreign bodies, food impaction.
** Intramural
*** E.g. neoplasia
** Extrinsic
*** E.g. adhesions, neoplasia and prostate enlargement.
====Intraluminal Obstruction====
=====Foreign Bodies=====
* Foreign bodies of all types can be found in the intestines.
* While some may pass through posing no problems, others can cause acute obstruction,
* Quite common in dogs
** Rare in other species - tend to lodge in the oesophagus or in one of the ruminant [[Stomach and Abomasum - Anatomy & Physiology|stomachs]].)
** Enteroliths can be seen in horses greater than 4 years of age.
*** Are stones consisting of magnesium ammonium phosphate around a central nidus (often a metallic foreign body)
*** Typically lodge at the pelvic flexure or the transverse [[Colon - Anatomy & Physiology|colon]].
* '''Clinical'''
** Obstruction at pylorus produces repeated [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|vomiting]].
** Obstrustion lower down gives less dramatic effect.
*** Is still a problem if in the middle of the [[Small Intestine - Anatomy & Physiology|small intestine]]s.
*** May be vague signs; some [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|vomiting]] and off food.
* '''Diagnosis'''
** May not show up well radiographically (unless radio-opaque) for several days.
*** May also be objects that are semi solid or soft, e.g.
**** String
**** Plastic bags
**** Stringy things, like pieces of material- particularly in puppies.
** Make all of intestines have knotted appearance.
** May be seen in horses with baler twine.
* '''Pathogenesis'''
** Smooth, round objects, such as golf balls, lodge especially near the pylorus or lower down.
** Occasionally in cattle (piece of rope or piece of tarpaulin) produces a tangled mass in [[The Rumen - Anatomy & Physiology|rumen]].
** Cause pressure necrosis and eventually perforation.
** Foreign bodies can also be chronic, remaining for long periods of time without causing disturbance.
=====Impaction=====
* Impaction of the [[Colon - Anatomy & Physiology|colon]] can occur in all species.
** Dog and cat - main cause is dehydrated faecal material.
** Horse - faeces, digesta, sand, or fibrous material can all contribute.
*** There are certain predisposing factors:
**** Poor dentition
**** Water deprivation
**** A high roughage diet
**** General debility.
*Antihelminthic administration or large parasite burdens can also lead to impaction.
====Extrinsic Obstruction====
* Obstruction of the intestine due to external factors such as tumours, abscesses, and fibrous adhesions is a common occurrence.
=====Inflammatory Adhesions=====
[[Image:colon_adhesions_horse.jpg|thumb|right|150px|colonic adhesions in the horse (Courtesy of Elspeth Milne)]]
* Arise following gut perforation, peritonitis or surgery.
* Consist of fibrous tissue bands that may:
** Restrict intestinal motility
** Cause kinks in the mesentery.
=====Prostatic Enlargement=====
* In the dog
* Can lead to compression of the [[Rectum - Anatomy & Physiology|rectum]]
=====Neoplasia=====
* Neoplasi in structures adjacent to the intestines can spread and cause external compression.
* Pancreatic tumours in particular can extend and impinge on the [[Duodenum - Anatomy & Physiology|duodenum]].
* Pedicles of tumours such as lipomas in horses can become wound in loops of intestine leading to obstruction and possible strangulation.
[[Image:Pedunc_lipoma_closeup.jpg|thumb|right|150px|Closeup of a pedunculated lipoma (Courtesy of Elspeth Milne)]]
* '''Clinical'''
** Occasional [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|vomiting]] and ntermittent [[Intestine Diarrhoea - Pathology|diarrhoea]] over several weeks.
* '''Pathogenesis'''
** Seen occasionally in cat (rarer in dog)
** Usually towards end of intestines
*** E.g. at the ileocaecocolic valve.
** Gut proximal to tumour becomes thickened due to hypertrophy of smooth muscle as a result of trying to force ingesta past progessively narrowing lumen.
** Produces "hose pipe intestine".
** Seen with carcinoma, lymphoma, leiomyoma and other tumours.[[Category:Obstruction, Intestinal]]
** Acute obstruction usually involves the upper or middle [[Small Intestine - Anatomy & Physiology|small intestine]]
** Chronic obstruction typically occurs in the distal [[Small Intestine - Anatomy & Physiology|small intestine]] or [[Large Intestine - Anatomy & Physiology|large intestine]].
* Three main categories of causes of obstruciton:
** Intraluminal
*** E.g. foreign bodies, food impaction.
** Intramural
*** E.g. neoplasia
** Extrinsic
*** E.g. adhesions, neoplasia and prostate enlargement.
====Intraluminal Obstruction====
=====Foreign Bodies=====
* Foreign bodies of all types can be found in the intestines.
* While some may pass through posing no problems, others can cause acute obstruction,
* Quite common in dogs
** Rare in other species - tend to lodge in the oesophagus or in one of the ruminant [[Stomach and Abomasum - Anatomy & Physiology|stomachs]].)
** Enteroliths can be seen in horses greater than 4 years of age.
*** Are stones consisting of magnesium ammonium phosphate around a central nidus (often a metallic foreign body)
*** Typically lodge at the pelvic flexure or the transverse [[Colon - Anatomy & Physiology|colon]].
* '''Clinical'''
** Obstruction at pylorus produces repeated [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|vomiting]].
** Obstrustion lower down gives less dramatic effect.
*** Is still a problem if in the middle of the [[Small Intestine - Anatomy & Physiology|small intestine]]s.
*** May be vague signs; some [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|vomiting]] and off food.
* '''Diagnosis'''
** May not show up well radiographically (unless radio-opaque) for several days.
*** May also be objects that are semi solid or soft, e.g.
**** String
**** Plastic bags
**** Stringy things, like pieces of material- particularly in puppies.
** Make all of intestines have knotted appearance.
** May be seen in horses with baler twine.
* '''Pathogenesis'''
** Smooth, round objects, such as golf balls, lodge especially near the pylorus or lower down.
** Occasionally in cattle (piece of rope or piece of tarpaulin) produces a tangled mass in [[The Rumen - Anatomy & Physiology|rumen]].
** Cause pressure necrosis and eventually perforation.
** Foreign bodies can also be chronic, remaining for long periods of time without causing disturbance.
=====Impaction=====
* Impaction of the [[Colon - Anatomy & Physiology|colon]] can occur in all species.
** Dog and cat - main cause is dehydrated faecal material.
** Horse - faeces, digesta, sand, or fibrous material can all contribute.
*** There are certain predisposing factors:
**** Poor dentition
**** Water deprivation
**** A high roughage diet
**** General debility.
*Antihelminthic administration or large parasite burdens can also lead to impaction.
====Extrinsic Obstruction====
* Obstruction of the intestine due to external factors such as tumours, abscesses, and fibrous adhesions is a common occurrence.
=====Inflammatory Adhesions=====
[[Image:colon_adhesions_horse.jpg|thumb|right|150px|colonic adhesions in the horse (Courtesy of Elspeth Milne)]]
* Arise following gut perforation, peritonitis or surgery.
* Consist of fibrous tissue bands that may:
** Restrict intestinal motility
** Cause kinks in the mesentery.
=====Prostatic Enlargement=====
* In the dog
* Can lead to compression of the [[Rectum - Anatomy & Physiology|rectum]]
=====Neoplasia=====
* Neoplasi in structures adjacent to the intestines can spread and cause external compression.
* Pancreatic tumours in particular can extend and impinge on the [[Duodenum - Anatomy & Physiology|duodenum]].
* Pedicles of tumours such as lipomas in horses can become wound in loops of intestine leading to obstruction and possible strangulation.
[[Image:Pedunc_lipoma_closeup.jpg|thumb|right|150px|Closeup of a pedunculated lipoma (Courtesy of Elspeth Milne)]]
* '''Clinical'''
** Occasional [[Control of Feeding - Anatomy & Physiology#The Vomit Reflex|vomiting]] and ntermittent [[Intestine Diarrhoea - Pathology|diarrhoea]] over several weeks.
* '''Pathogenesis'''
** Seen occasionally in cat (rarer in dog)
** Usually towards end of intestines
*** E.g. at the ileocaecocolic valve.
** Gut proximal to tumour becomes thickened due to hypertrophy of smooth muscle as a result of trying to force ingesta past progessively narrowing lumen.
** Produces "hose pipe intestine".
** Seen with carcinoma, lymphoma, leiomyoma and other tumours.[[Category:Obstruction, Intestinal]]