Difference between revisions of "Category:Intestine - Mechanical Obstruction"

Revision as of 12:34, 31 May 2010

Acute of chronic mechanical obstruction of the intestine can occur in all species.
- Acute obstruction usually involves the upper or middle small intestine
- Chronic obstruction typically occurs in the distal small intestine or 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, Intestinal

Impaction

Impaction of the 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

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

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.
Pedicles of tumours such as lipomas in horses can become wound in loops of intestine leading to obstruction and possible strangulation.

Closeup of a pedunculated lipoma (Courtesy of Elspeth Milne)

Clinical
- Occasional vomiting and ntermittent 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.

Subcategories

This category has only the following subcategory.

I

► Impaction - Horse‎ (10 P)

Pages in category "Intestine - Mechanical Obstruction"

The following 10 pages are in this category, out of 10 total.

A

I

M

Meconium Impaction - Horse

N

Neoplasia, Intestinal

P

Prostatic Enlargement

@@ Line 4: / Line 4: @@
 * Three main categories of causes of obstruciton:
 ** Intraluminal
-*** E.g. foreign bodies, food impaction.
+*** E.g. [[Foreign Bodies, Intestinal|foreign bodies]], food impaction.
 ** Intramural
 *** E.g. neoplasia
@@ Line 12: / Line 12: @@
 ====Intraluminal Obstruction====
-=====Foreign Bodies=====
+=====[[Foreign Bodies, Intestinal]]=====
-* 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=====