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==Description==  

==Description==  

If the hernial ring narrows or if the displaced organs expand, the contents of the hernial sac may be trapped or 'incarcerated'.  These structures cannot be moved back to their original position and surgical intervention is usually required to increase the size of the hernial ring.  Incarcerated hernias also carry a greater risk of strangulation.

If the hernial ring narrows or if the displaced organs expand, the contents of the hernial sac may be trapped or 'incarcerated'.  These structures cannot be moved back to their original position and surgical intervention is usually required to increase the size of the hernial ring.  Incarcerated hernias also carry a greater risk of strangulation.

===Strangulaton===

===Strangulation===

The contents of the hernial sac are trapped and their blood supply is impaired.  Initially, only venous drainage is reduced leading to oedema and congestion but infarction may occur if the arterial blood supply is also affected.  Strangulated loops of small intestine are unable to maintain an effective barrier against gastro-intestinal bacteria and bacterial endotoxin, leading to peritonitis, sepsis and endotoxic shock.  The intestine may also rupture causing acute septic peritonitis.  

The contents of the hernial sac are trapped and their blood supply is impaired.  Initially, only venous drainage is reduced leading to oedema and congestion but infarction may occur if the arterial blood supply is also affected.  Strangulated loops of small intestine are unable to maintain an effective barrier against gastro-intestinal bacteria and bacterial endotoxin, leading to peritonitis, sepsis and endotoxic shock.  The intestine may also rupture causing acute septic peritonitis.  

==Types of hernia==

==Types of hernia==

*'''Umbilical hernias''' are congenital and result from a failure of closure of the foetal umbilical canal.  They occur in all of the major domestic species.

*'''Umbilical hernias''' are congenital and result from a failure of closure of the foetal umbilical canal.  They occur in all of the major domestic species.

*'''Diaphragmatic hernias''' may be congenital or, much more commonly, [[Diaphragmatic Rupture|diaphragmatic ruptures]] may occur following blunt abdominal trauma in small animals.  Congenital diaphragmaic hernias are an unusual cause of small intestinal incarceration and strangulation in horses, manifesting as severe colic.  If the septum transversum (the embryonic structure that forms the diaphragm) fails to develop fully, congenital [[Hernia, Peritoneopericardial Diaphragmatic|Peritoneal-Pericardial-Diaphragmatic hernias]] (PPDH) or [[Hernia, Pleuroperitoneal Diaphragmatic|Pleuroperitoneal hernias]] may occur.

*'''Diaphragmatic hernias''' may be congenital or, much more commonly, [[Diaphragmatic Rupture|diaphragmatic ruptures]] may occur following blunt abdominal trauma in small animals.  Congenital diaphragmatic hernias are an unusual cause of small intestinal incarceration and strangulation in horses, manifesting as severe colic.  If the septum transversum (the embryonic structure that forms the diaphragm) fails to develop fully, congenital [[Hernia, Peritoneopericardial Diaphragmatic|Peritoneal-Pericardial-Diaphragmatic hernias]] (PPDH) or [[Hernia, Pleuroperitoneal Diaphragmatic|Pleuroperitoneal hernias]] may occur.

*'''Inguinal/scrotal hernias''' may be congenital or acquired.  Congenital hernias are rare and usually occur in young male dogs with late testicular descent.  It is suggested that this process holds the inguinal canal open for longer than normal, allowing abdominal organs to displace into them.  Acquired hernias occur in obese animals (in which the canal is held open by the local accumulation of fat) and in older entire bitches (in which the gravid uterus may be herniated).  Inguinal hernias also occur in stallions after castration and may cause severe colic.

*'''Inguinal/scrotal hernias''' may be congenital or acquired.  Congenital hernias are rare and usually occur in young male dogs with late testicular descent.  It is suggested that this process holds the inguinal canal open for longer than normal, allowing abdominal organs to displace into them.  Acquired hernias occur in obese animals (in which the canal is held open by the local accumulation of fat) and in older entire bitches (in which the gravid uterus may be herniated).  Inguinal hernias also occur in stallions after castration and may cause severe colic.

*'''[[Perineal Hernia| Perineal hernias]]''' are true hernias where abdominal organs move into space created by the weakening or rupture of muscles forming the pelvic diapragm and anus.  Older male entire dogs are particularly affected and these often have concurrent enlargement of the prostate gland.

*'''[[Perineal Hernia| Perineal hernias]]''' are true hernias where abdominal organs move into space created by the weakening or rupture of muscles forming the pelvic diapragm and anus.  Older male entire dogs are particularly affected and these often have concurrent enlargement of the prostate gland.

==References==

==References==

[http://w3.vet.cornell.edu/nst/nst.asp?Fun=Image&imgID=22114 Image of congenital umbilical hernia in a pig from Cornell Veterinary Medicine]

[http://w3.vet.cornell.edu/nst/nst.asp?Fun=Image&imgID=22114 Image of congenital umbilical hernia in a pig from Cornell Veterinary Medicine]

[[Category:To_Do_-_James]][[Category:Intestine_-_Physical_Disturbances]]

[[Category:To_Do_-_James]][[Category:Intestine_-_Physical_Disturbances]]

[[Category:Peritoneal_Cavity_-_Developmental_Pathology]][[Category:Dog]][[Category:Cat]][[Category:Horse]][[Category:Donkey]][[Category:Cattle]][[Category:Sheep]]

[[Category:Peritoneal_Cavity_-_Developmental_Pathology]][[Category:Dog]][[Category:Cat]][[Category:Horse]][[Category:Donkey]][[Category:Cattle]][[Category:Sheep]]

[[Category:To_Do_-_Review]]

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