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Category:Intestine - Physical Disturbances (view source)
Revision as of 12:17, 31 May 2010
, 12:17, 31 May 2010Created page with ' == Category:Obstruction, Intestinal == ==Positional Changes/ Displacements== ===Hernia=== * A hernia is defined as the displacement of the [[Small Intestine - Anatomy…'
== [[:Category:Obstruction, Intestinal]] ==
==Positional Changes/ Displacements==
===Hernia===
* A hernia is defined as the displacement of the [[Small Intestine - Anatomy & Physiology|small intestine]] through a normal or pathologic foramina.
** Occasionally, the [[Large Intestine - Anatomy & Physiology|large intestine]] is involved.
====Pathogenesis====
* Associated with trauma or the weakening of tissues.
** For example,
*** Old age
*** Pregnancy
*** Straining
*** Wound dehiscence.
* Most hernias are external[[Image:hernial sac.jpg|thumb|right|150px|Diagram of a hernial sac (Courtesy of Elspeth Milne)]]
** Contents pass through a hernial ring in the abdominal wall.
** Are covered with parietal peritoneum, soft tissue and skin.
*** A hernial sac.
====Sequelae====
* The sequelae depend on whether the hernia is reducible, or is an incarceration.
=====Reducible hernia=====
* The hernial contents are freely moveable.
* There are NO sequelae.
=====Incarceration=====
* The [[Small Intestine - Anatomy & Physiology|small intestine]] contents are trapped.
** The hernia is non-reducible.
* Venous drainage is obstruced.
** Oedema
** Congestion
* Adhesions form between the contents and the sac.
* Accumulated gas/ ingesta distends the herniated viscus.
* Obstruction of lumen leads to
** Rupture
** Peritonitis
** Death.
====Types of hernia====
* '''Umbilical''' - usually congenital.
* '''Diaphragmatic''' - common following road traffic accidents in the dog and cat.
* '''Inguinal/scrotal''' - may be:
** Congenital
** Acquired
*** E.g. post castration of stallion
* '''Perineal''' - old male dogs with prostate enlargement.
* '''Ventral''' -wound site breakdown, old mares
* '''Omental/mesenteric''' - internal hernias.
[[Image:volvulus.jpg|thumb|right|150px|Volvulus (Courtesy of Bristol BioMed Image Archive)]]
===Volvulus===
* A twist about the long axis of the gut.
* Generally in the [[Small Intestine - Anatomy & Physiology|small intestine]].
* Intense congestion
** Often almost black.
* Mostly in young animals
** Especially calves and piglets
** Occasionally sheep and dogs.
** Occasionally in greater mesentery of horse.
====Pathogenesis====
* Loop of bowel twists through 180 degrees around mesentery to produce obstruction of lumen.
* Proximal the the obstruction, the bowel becomes rapidly distended.
** Venous return is first shut off, but the arterial supply remains.
*** Bowel becomes engorged with blood.
** Produces rapid death.
* Bowel becomes hypoxic.[[Image:Large_colon_torsion_horse.jpg|thumb|right|150px|Torsion of the large colon in the horse (Courtesy of Elspeth Milne)]]
** Toxic material and bacteria pass through the anoxic wall of bowel.
* In piglets may see whole of [[Small Intestine - Anatomy & Physiology|small intestine]] twisted around root of mesentery.
** Very little can be done to resolve this** Produces rapid death
===Torsion===
* A twist across the long axis of gut.
* Most common in the [[Colon - Anatomy & Physiology|colon]] of the pig and the horse
===Intussusception===
[[Image:intussusception.jpg|thumb|right|150px|Diagram of intussuscception (Courtesy of Elspeth Milne)]]
* Telescoping of one segment of the bowel into another.
* Occurs in all species.
** Particularly in young dogs.
* Can occur in the [[Small Intestine - Anatomy & Physiology|small intestine]], [[Caecum - Anatomy & Physiology|caecum]] or [[Colon - Anatomy & Physiology|colon]].
====Clinical====
* Intussusception is a less acute type of obstruction.
* Produces intermittent [[Intestine Diarrhoea - Pathology|diarrhoea]].
* Animals go downhill in a few days.
* Palpation of abdomen may allow a "Cumberland sausage" effect to be felt.
** NB abdominal palpation in small animal, rectal palpation in large animal.
====Pathogenesis====
* Proximal intestine invaginates into lower part of intestine.[[Image:intussuceptionphoto.jpg|thumb|right|150px|Intersusception (Courtesy of Bristol BioMed Image Archive)]]
** Takes mesenteric attachment with it.
* Compression of the mesenteric vessels obstructs venous drainage of the gut, resulting in venous congestion.
** Swelling (oedema/congestion) arises.
*** Inflammatory exudate from serous surface.
**** Fibrinous adhesions form between surfaces making structure irreducible.
* May progress to necrosis and gangrene of the tissue.
* There is often functional obstruction to bowel.
* May rupture, leading to peritonitis and death.
*Associated with anything that raises peristalsis e.g. change in diet, bacterial infection.
** Foreign body
** Intramural abscess/tumour
** Heavy parasitism
** Previous intestinal surgery
** Enteritis
** Other motility disorders.
** Change in diet
** Bacterial infection
====Pathology====
* When operate or at post mortem see large sausage shaped distension of length of intestine.
* Intussusception may occur post mortem
** There are no associated changes
** The condition is easilt reducible.
===Rectal prolapse===
* Pig, sheep, cattle
* Related to prolonged tenesmus, e.g.
** Colitis
** Urinary infection
** Obstruction
** Hepatic failure.
'''References''' <br /br>
Brown CC, Baker DC, Barker IK: Alimentary System. In: Jubb, Kennedy and Palmer's Pathology of Domestic Animals, ed. Maxie MG, 5th ed., pp. 1-296. Elsevier, Philadelphia, PA, 2007.
McGavin DM & Zachary, JF: Pathologic Basis of Veterinary Disease, 4th ed, pp. 301-393.Elsevier, St. Louis, Missouri, 2007.
[[Category:Intestines, Small and Large - Pathology]]