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==Introduction==
[[Image:intussusception.jpg|thumb|right|300px|Diagram of intussuscception (Courtesy of Elspeth Milne)]]
'''Intussusception''' is the invagination of one portion of the gastrointestinal tract into the lumen of the adjacent portion. The '''intussusceptum''' is the invaginated segment and the '''intussuscipien''' is the enveloping segment. A normograde intussusception is most common, but retrograde intussusception has also been reported.
[[Image:intussusception.jpg|thumb|right|150px|Diagram of intussuscception (Courtesy of Elspeth Milne)]]
Intussusceptions can be classified according to their location in the gastrointestinal tract. They usually occur in regions where there is a significant change in lumen diameter, such as ileocolic and gastroesphageal junctions. Ileocolic intussusceptions are most common, they frequently protrude from the rectum and must be distinguished from a rectal prolapse. In the case of an intussusception, it is possible to pass a probe next to the anus, but not in a [[Rectal Prolapse - Cat and Dog|rectal prolapse]].
Depending on the site and severity, an intussusception results in a partial or complete obstruction to the gastrointestinal tract causing hypovolaemia, dehydration and shock. The condition is potentially serious and should be treated as an emergency.
Also see: [[Intussusception - Horse|Intussusception in horses]].
===Pathogenesis===
===Pathogenesis===
Intussusception results from abnormal peristalsis. Vigorous contractions force the more proximal intestine to invaginate into the adjacent distal portion, taking its mesenteric attachment with it. Obstruction of the gastrointestinal tract causes distention which may lead to rupture and peritonitis. Compression of the mesenteric vessels cause vascular compromise to the intestine, resulting in venous congestion, oedema and if the aterial supply is damaged, full thickness necrosis. An inflammatory exudate is released from the serosal surface and fibrinous adhesions may form, making the structure irreducible.
Intussusception normally occurs due to gastrointestinal disease, although it is often hard to identify the cause. It is associated with any condition that increases peristalsis such as
* Enteritis
* Foreign body
* Heavy parasitism
Intussusception normally occurs due to gastrointestinal disease, although it is often hard to identify the cause. Parasites, infectious enteritis, metabolic disorders, foreign bodies, history of recent intestinal surgery, intestinal masses have all been known to associate with intussusception. Chronic intussusception can occur with little haemodynamic changes.
* Previous intestinal surgery
* Intramural abscess/tumour
* Motility disorders.
* Change in diet
* Bacterial infection
==Signalment==
==Signalment==
Intussusception occurs in dogs and cats, but gastroesophageal intussusception has only been reported in dogs.
Intussusception occurs in dogs and cats, but gastroesophageal intussusception has only been reported in dogs.
German shepherd dogs and Siamese cats are over represented. German Shepherd dogs are particularly predisposed to gastroesophageal intussusception.
German shepherd dogs and Siamese cats are over represented. German Shepherd dogs are particularly predisposed to gastroesophageal intussusception.
Young animals are most commonly affected, 80% of cases are less than a year old.
==Diagnosis==
==Diagnosis==
Clinical signs vary depending on location, duration and the degree of obstruction and vascular compromise.
Clinical signs vary depending on location, duration and the degree of obstruction and vascular compromise.
====Acute Intussusception====
====Acute Intussusception====
*[[Stomach and Abomasum Consequences of Gastric Disease - Pathology|Vomiting]]
*[[Vomiting|Vomiting]]
*Regurgitation
*Regurgitation
*Haematemesis
*Haematemesis
*Abdominal discomfort
*Abdominal discomfort
*collapse
*Collapse
*Palpable sausage-shaped mass in the abdomen
*Palpable abdominal tubular mass
*Diarrhoea; bloody and mucoid
*Diarrhoea- bloody and mucoid
*Tenesmus and Haematochezia; in cases of ileocaecocolic intussusception
*Tenesmus and Haematochezia in cases of ileocaecocolic intussusception
*Ileocolic intussusception protruding through the anus
====Chronic Intussusception====
====Chronic Intussusception====
*Intermittent diarrhoea, which may be bloody and mucoid
*Intermittent diarrhoea- bloody and mucoid
*Tenesmus
*Tenesmus
*Depression
*Depression
===Radiography===
===Radiography===
Plain abdominal radiographs do not always provide a definitive diagnosis. In cases of complete obstruction distented loops of intestine and a tubular soft tissue mass are usually obvious, but a partial obstruction will produce much more subtle signs which may be missed.
Plain abdominal radiographs do not always provide a definitive diagnosis. In cases of complete obstruction distented loops of intestine and a tubular soft tissue mass are usually obvious, but a partial obstruction will produce much more subtle signs which may be missed.
A barium enema or upper gastrointestinal contrast study can be useful in identifying the site of obstruction but may result in delay of treatment and should be used with care as leakage of contrast into the abdominal cavity will result in peritonitis.
A barium enema or upper gastrointestinal contrast study can be useful in identifying the site of obstruction but may result in delay of treatment and should be used cautiously as leakage of contrast into the abdominal cavity will result in peritonitis.
The classic appearance of an intussusception is described as a 'coiled spring'.
===Ultrasound===
===Ultrasound===
Abdominal ultrasound will reveal a cylindrical mass with layering of the intestinal wall. On a transverse section, a hyperechoic target mass in the centre with multiple hyperechoic and hypoechoic concentric ring is seen. On a longitudinal section, multiple hyperechoic and hypoechoic lines are seen. The intestines may also be hypomotile and the intestine proximal to the obstruction may be distented with fluid.
Abdominal ultrasound will reveal a cylindrical mass with layering of the intestinal wall. The intestines may also be hypomotile, with distension proximal to the obstruction.
===Endoscopy===
===Endoscopy===
Intussusception may occur due to post mortem change, in this case there are no other associated changes and the invaginated intestine is easily reducible.
Intussusception may occur due to post mortem change, in this case there are no other associated changes and the invaginated intestine is easily reducible.
==Treatment==
[[Principles of Fluid Therapy|Fluid therapy]] and correction of electrolyte and acid-base abnormalities should be carried out prior to surgical correction.
'''Surgery''' is required to manually reduce the intussusception, it may be necessary to '''resect and anastomose''' the intestine in cases where the adhesions have formed. This decision depends on the viability of the intestines, as determined by the colour, vascular supply and presence or absence of peristalsis.It is important to preserve as much of the intestine as possible to avoid [[Short Bowel Syndrome|short bowel syndrome]].
Complications include dehiscence at the site of anastomosis, [[Peritonitis - Cats and Dogs|peritonitis]], recurrence (11-20%, most common within 1-5 days post surgery), ileus, intestinal obstruction and short bowel syndrome.
Recurrence can be prevented by '''enteroplication''' of the small intestine, or by a left-sided gastroplexy of the fundus in cases of gastroesophageal intussusception.
==Prognosis==
This depends on the location, completeness and duration of the intusussception. The prognosis is good in animals treated with early surgical intervention and aggressive supportive care. The prognosis is poor for animals with perforated intestine and peritonitis.
{{Learning
|Vetstream = [https://www.vetstream.com/canis/Content/Disease/dis00651.asp, Canine intussusception]<br>[https://www.vetstream.com/canis/Content/Illustration/ill00400.asp, Intussusception barium radiograph]
|flashcards = [[Small Animal Abdominal and Metabolic Disorders Q&A 14]]
|literature search = [http://www.cabdirect.org/search.html?q=title%3A%28Intussusception%29 Intussusception publications]
[http://www.cabdirect.org/search.html?q=%28%28od%3A%28dogs%29%29%29+AND+%28%28title%3A%28Intussusception%29%29%29 Intussusception in dogs publications]
[http://www.cabdirect.org/search.html?q=%28%28od%3A%28cats%29%29%29+AND+%28%28title%3A%28Intussusception%29%29%29 Intussusception in cats publications]
==Prognosis==
[http://www.cabdirect.org/search.html?q=%28%28od%3A%28horses%29%29%29+AND+%28%28title%3A%28Intussusception%29%29%29 Intussusception in horses publications]
[http://www.cabdirect.org/search.html?q=%28%28od%3A%28cattle%29+OR+od%3A%28sheep%29+OR+od%3A%28goats%29+OR+od%3A%28pigs%29%29%29+AND+%28%28title%3A%28Intussusception%29%29%29 Intussusception in farm animals publications]
}}
==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''.
*Tilley, L.P. and Smith, F.W.K.(2004)'''The 5-minute Veterinary Consult(Third edition)''' ''Lippincott, Williams & Wilkins''.
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