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==Introduction==

==Description==

'''Perineal hernia''' is the protrusion of pelvic or abdominal viscera through the structures of the weakened or ruptured pelvic diaphragm, causing displacement of the perineal skin.  The pelvic diaphragm is composed of the coccygeus, levator ani and external anal sphincter muscles and, due to its proximity to these structures, the rectum is the organ most commonly involved in perineal hernias.  Perineal hernias can be unilateral or bilateral and, depending of their location, they can be further classified as dorsal, ventral, sciatic or caudal hernias.  The herniated content is contained by the perineal fascia and, since the parietal peritoneum is usually intact, this constitutes a true [[Hernia|hernial sac]].  The sac may contain pelvic or retroperitoneal fat, peritoneal fluid, a deviation, dilation or sacculation of the rectum, a rectal diverticulum, the prostate gland, the urinary bladder (which may be retroflexed) or the small intestine and any of these organs may become [[Hernia|incarcerated or stangulated]].  In cats, the sac frequently only contains the rectum.   

'''Perineal hernia''' is the protrusion of pelvic or abdominal viscera through the structures of the weakened or ruptured pelvic diaphragm, causing displacement of the perineal skin.  The pelvic diaphragm is composed of the coccygeus, levator ani and external anal sphincter muscles and, due to its proximity to these structures, the rectum is the organ most commonly involved in perineal hernias.  Perineal hernias can be unilateral or bilateral and, depending of their location, they can be further classified as dorsal, ventral, sciatic or caudal hernias.  The herniated content is contained by the perineal fascia and, since the parietal peritoneum is usually intact, this constitutes a true [[Hernia|hernial sac]].  The sac may contain pelvic or retroperitoneal fat, peritoneal fluid, a deviation, dilation or sacculation of the rectum, a rectal diverticulum, the prostate gland, the urinary bladder (which may be retroflexed) or the small intestine and any of these organs may become [[Hernia|incarcerated]] or [[Hernia|stangulated]].  In cats, the sac frequently only contains the rectum.   

The cause of perineal hernia is not know but several factors have been discussed, all of which are thought to contribute to progressive weakness and atrophy of the muscles of the pelvic diaphragm.  These include:

The cause of perineal hernia is not know but several factors have been discussed, all of which are thought to contribute to progressive weakness and atrophy of the muscles of the pelvic diaphragm.  These include:

*The rectum loses lateral support on the affected side(s) and, on digital rectal examination, the skin over the hernia can be elevated because the rectum is no longer contained within the pelvic cavity.

*The rectum loses lateral support on the affected side(s) and, on digital rectal examination, the skin over the hernia can be elevated because the rectum is no longer contained within the pelvic cavity.

*Constipation/obstipation, dyschezia and tenesmus result from alterations to the normal contours of the rectum, including deviations or flexures, sacculations (unilateral dilations), bilateral dilations and pulsion diverticula.  Continued tenesmus may worsen the extent of the hernia.

*Constipation/obstipation, dyschezia and tenesmus result from alterations to the normal contours of the rectum, including deviations or flexures, sacculations (unilateral dilations), bilateral dilations and pulsion diverticula.  Continued tenesmus may worsen the extent of the hernia.

*Chronic tenesmus and bilateral loss of rectal support may result in [[Rectal Prolapse|rectal prolapse]].

*Chronic tenesmus and bilateral loss of rectal support may result in [[Rectal Prolapse - Cat and Dog|rectal prolapse]].

Signs due to '''incarceration or strangulation''' of organs and necessitating emergency treatment

Signs due to '''incarceration or strangulation''' of organs and necessitating emergency treatment

==Prognosis==

==Prognosis==

The rate of recurrence is around 15% one year after surgical herniorraphy.  Cases involving bladder retroflexion have the poorest prognosis and, although cases managed medically may have an acceptable quality of life, there is always a danger that the bladder or another organ will be incarcerated and strangulated in the hernial sac.

The rate of recurrence is around 15% one year after surgical herniorraphy.  Cases involving bladder retroflexion have the poorest prognosis and, although cases managed medically may have an acceptable quality of life, there is always a danger that the bladder or another organ will be incarcerated and strangulated in the hernial sac.

==References==

==References==

*Hall, E.J, Simpson, J.W. and Williams, D.A. (2005) '''BSAVA Manual of Canine and Feline Gastroenterology (2nd Edition)''' ''BSAVA''

*Hall, E.J, Simpson, J.W. and Williams, D.A. (2005) '''BSAVA Manual of Canine and Feline Gastroenterology (2nd Edition)''' ''BSAVA''

*Nelson, R.W. and Couto, C.G. (2009) '''Small Animal Internal Medicine (Fourth Edition)''' ''Mosby Elsevier''.

*Nelson, R.W. and Couto, C.G. (2009) '''Small Animal Internal Medicine (Fourth Edition)''' ''Mosby Elsevier''.

[[Category:Recto-Anal_-_Pathology]]

[[Category:Recto-Anal_-_Pathology]]

[[Category:To_Do_-_James]]

[[Category:Rectal and Anal Diseases - Dog]][[Category:Rectal and Anal Diseases - Cat]]

[[Category:Expert_Review]]

[[Category:Expert_Review]]