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, 12:43, 1 June 2010
* 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)]][[Category:Intestine_-_Physical_Disturbances]]