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