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==Description==

==Introduction==

 

The most common condition causing simple obstruction of the small intestinal lumen.<ref name="Merck">Merck & Co (2008) '''The Merck Veterinary Manual (Eighth Edition)''', ''Merial''.</ref>

The most common condition causing simple obstruction of the small intestinal lumen.<ref name="Merck">Merck & Co (2008) '''The Merck Veterinary Manual (Eighth Edition)''', ''Merial''.</ref>

==Signalment==

==Signalment==

Adult horses

Adult horses

==Aetiology==

==Aetiology==

In the southeastern United States, feeding of poor quality coastal Bermuda hay and lack of administration of the anthelmintic pyrantel pamoate have been implicated as risk factors.<ref>Little, D, Blikslager, A.T (2002) Factors associated with development of ileal impaction in horses with surgical colic:78 cases (1986-2000).  ''Equine Vet J'' 34(5):464-8.</ref>  It is proposed that when this forage has a high fibre content, there is an increased proportion of thin fibres which are prematurely swallowed.<ref>Blikslager, A.T (2010) ''Obstructive Disorders of the Gastrointestinal Tract'' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), Chapter 15, ''Saunders''.</ref>  Sudden feed changes may also contribute.<ref>Parks, A.H.A, Allen, D (1998) ''The purported role of coastal Bermuda hay in the etiology of ileal impactions: results of a questionnaire (abstract), 6th Equine Colic Research Symposium'', University of Georgia, p37.  In: Blikslager, A.T (2010) ''Obstructive Disrodersof the Gastrointestinal Tract'' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), Chapter 15, ''Saunders''.</ref>  In the UK, infection with the tapeworm [[Anoplocephala|''Anoplocephala perfoliata'']] is an important risk factor.  Proudman and colleagues (1998) found that more than 80% of ileal impactions were associated with serological or faecal evidence of tapeworm infection.<ref>Proudman, C.J, French, N.P, Trees, A.J (1998) Tapeworm infection is a significant risk factor for spasmodic colic and ileal impaction colic in the horse.  ''Equine Vet J'', 30:194-199.</ref>  ''Anoplocephala perfoliata'' infects up to 60% of horses in some geographical areas and has also been implicated as a risk factor for bowel irritation and spasmodic colic.<ref name="Kania">Kania, S.A, Reinemeyer, C.R (2005) ''Anoplocephala perfoliata'' coproantigen detection: a preliminary study.  ''Vet Parasitol'', 127(2):115-9.</ref>Impaction may also develop secondary to spastic contractions of the ileal musculature against ingesta.<ref name="Merck">Merck & Co (2008) '''The Merck Veterinary Manual (Eighth Edition)''', ''Merial''.</ref>

In the southeastern United States, feeding of poor quality coastal Bermuda hay and lack of administration of the anthelmintic pyrantel pamoate have been implicated as risk factors.<ref>Little, D, Blikslager, A.T (2002) Factors associated with development of ileal impaction in horses with surgical colic:78 cases (1986-2000).  ''Equine Vet J'' 34(5):464-8.</ref>  It is proposed that when this forage has a high fibre content, there is an increased proportion of thin fibres which are prematurely swallowed.<ref>Blikslager, A.T (2010) ''Obstructive Disorders of the Gastrointestinal Tract'' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), Chapter 15, ''Saunders''.</ref>  Sudden feed changes may also contribute.<ref>Parks, A.H.A, Allen, D (1998) ''The purported role of coastal Bermuda hay in the etiology of ileal impactions: results of a questionnaire (abstract), 6th Equine Colic Research Symposium'', University of Georgia, p37.  In: Blikslager, A.T (2010) ''Obstructive Disrodersof the Gastrointestinal Tract'' in Reed, S.M, Bayly, W.M. and Sellon, D.C (2010) '''Equine Internal Medicine''' (Third Edition), Chapter 15, ''Saunders''.</ref>  In the UK, infection with the tapeworm [[Anoplocephala|''Anoplocephala perfoliata'']] is an important risk factor.  Proudman and colleagues (1998) found that more than 80% of ileal impactions were associated with serological or faecal evidence of tapeworm infection.<ref>Proudman, C.J, French, N.P, Trees, A.J (1998) Tapeworm infection is a significant risk factor for spasmodic colic and ileal impaction colic in the horse.  ''Equine Vet J'', 30:194-199.</ref>  ''Anoplocephala perfoliata'' infects up to 60% of horses in some geographical areas and has also been implicated as a risk factor for bowel irritation and spasmodic colic.<ref name="Kania">Kania, S.A, Reinemeyer, C.R (2005) ''Anoplocephala perfoliata'' coproantigen detection: a preliminary study.  ''Vet Parasitol'', 127(2):115-9.</ref>Impaction may also develop secondary to spastic contractions of the ileal musculature against ingesta.<ref name="Merck">Merck & Co (2008) '''The Merck Veterinary Manual (Eighth Edition)''', ''Merial''.</ref>

==Clinical Signs==

==Clinical Signs==

Typical signs associated with [[Colic Diagnosis - Clinical Signs|small intestinal obstruction]]:

Typical signs associated with [[Colic Diagnosis - Clinical Signs|small intestinal obstruction]]:

*Moderate to severe colic

*Moderate to severe colic

==Diagnosis==

==Diagnosis==

Early [[Colic Diagnosis - Rectal Examination|rectal examination]] may reveal the impaction low in the right caudal abdominal quadrant.  Subsequent distention of the jejunum will be palpable ''per rectum'' but may preclude palpation of the impaction, thus the definitive diagnosis is often made at surgery.  Many horses with ileal impaction are delayed in their referral because initially their colic is mild and their condition deceptively stable.  [[Colic Diagnosis - Abdominocentesis|Abdominocentesis]] may show an elevated protein concentration if the impaction has persisted for more than about 18 hours.<ref name="Merck">Merck & Co (2008) '''The Merck Veterinary Manual (Eighth Edition)''', ''Merial''.</ref>  The most likely differential diagnosis is '''proximal jejunitis''', which can be challenging to rule out.

Early [[Colic Diagnosis - Rectal Examination|rectal examination]] may reveal the impaction low in the right caudal abdominal quadrant.  Subsequent distention of the jejunum will be palpable ''per rectum'' but may preclude palpation of the impaction, thus the definitive diagnosis is often made at surgery.  Many horses with ileal impaction are delayed in their referral because initially their colic is mild and their condition deceptively stable.  [[Colic Diagnosis - Abdominocentesis|Abdominocentesis]] may show an elevated protein concentration if the impaction has persisted for more than about 18 hours.<ref name="Merck">Merck & Co (2008) '''The Merck Veterinary Manual (Eighth Edition)''', ''Merial''.</ref>  The most likely differential diagnosis is '''proximal jejunitis''', which can be challenging to rule out.

==Treatment==

==Treatment==

[[Colic, Medical Treatment|'''Medical treatment''']] may be feasible if the pain is manageable, if repeated abdominocentesis demonstrates no evidence of intestinal degeneration, if there is no nasogastric reflux and if multiple tightly distended loops of small intestine are not present on rectal examination.  In this situation, balanced electrolyte solutions (administered IV) and analgesia may suffice.  Substances via nasogastric tube are contraindicated, even if reflux is absent, because the small intestinal distension and reduced motility proximally will prevent these reaching the impaction.  The response to medical intervention will be evidenced by a reduction in colic signs and an improvement in cardiovascular status.<ref name="Hanson 2">Hanson, R.R, Schumacher, J, Humburg, J, Dunkerley, S.C (1996) Medical treatment of horses with ileal impactions: 10 cases (1990-1994). ''J Am Vet Med Assoc'', 208(6):898-900.</ref>  Although medical treatment may resolve the impaction early on, surgery is typically required.

[[Colic, Medical Treatment|'''Medical treatment''']] may be feasible if the pain is manageable, if repeated abdominocentesis demonstrates no evidence of intestinal degeneration, if there is no nasogastric reflux and if multiple tightly distended loops of small intestine are not present on rectal examination.  In this situation, balanced electrolyte solutions (administered IV) and analgesia may suffice.  Substances via nasogastric tube are contraindicated, even if reflux is absent, because the small intestinal distension and reduced motility proximally will prevent these reaching the impaction.  The response to medical intervention will be evidenced by a reduction in colic signs and an improvement in cardiovascular status.<ref name="Hanson 2">Hanson, R.R, Schumacher, J, Humburg, J, Dunkerley, S.C (1996) Medical treatment of horses with ileal impactions: 10 cases (1990-1994). ''J Am Vet Med Assoc'', 208(6):898-900.</ref>  Although medical treatment may resolve the impaction early on, surgery is typically required.

==Complications==

==Complications==

Small intestinal distension and manipulation of the ileum at surgery may lead to '''post-operative ileus'''<ref>Blikslager, A.T, Bowman, K.F, Levine, J.F, ''et al.'' (1994) Evaluation of factors associated with postoperative ileus in horses: 31 cases (1990-1992).  ''J Am Vet Med Assoc'', 205:1748-1752.</ref> but the risk is reduced if the duration between disease onset and surgical intervention is decreased.<ref name="Hanson">Hanson, R.R, Wright, J.C, Schumacher, J, Baird, A.N, Humburg, J, Pugh, D.G (1998) Surgical reduction of ileal impactions in the horse: 28 cases. ''Vet Surg'', 27(6):555-60.</ref>  Depending on the degree of damage to the serosal surface of the small intestine at surgery, complications may develop several weeks after surgery due to intra-abdominal '''adhesions'''.<ref name="Merck">Merck & Co (2008) '''The Merck Veterinary Manual (Eighth Edition)''', ''Merial''.</ref>  Most of the problems related to adhesions are thought to occur within 2 months.<ref name="Baxter">Baxter, G.M, Broome, T.E, Moore, J.N (1989) Abdominal adhesions after small intestinal surgery in the horse.  ''Vet Surg'', 18(6):409-14.</ref>

Small intestinal distension and manipulation of the ileum at surgery may lead to '''post-operative ileus'''<ref>Blikslager, A.T, Bowman, K.F, Levine, J.F, ''et al.'' (1994) Evaluation of factors associated with postoperative ileus in horses: 31 cases (1990-1992).  ''J Am Vet Med Assoc'', 205:1748-1752.</ref> but the risk is reduced if the duration between disease onset and surgical intervention is decreased.<ref name="Hanson">Hanson, R.R, Wright, J.C, Schumacher, J, Baird, A.N, Humburg, J, Pugh, D.G (1998) Surgical reduction of ileal impactions in the horse: 28 cases. ''Vet Surg'', 27(6):555-60.</ref>  Depending on the degree of damage to the serosal surface of the small intestine at surgery, complications may develop several weeks after surgery due to intra-abdominal '''adhesions'''.<ref name="Merck">Merck & Co (2008) '''The Merck Veterinary Manual (Eighth Edition)''', ''Merial''.</ref>  Most of the problems related to adhesions are thought to occur within 2 months.<ref name="Baxter">Baxter, G.M, Broome, T.E, Moore, J.N (1989) Abdominal adhesions after small intestinal surgery in the horse.  ''Vet Surg'', 18(6):409-14.</ref>

==Prognosis==

==Prognosis==

The prognosis for survival is generally good.<ref name="Hanson">Hanson, R.R, Wright, J.C, Schumacher, J, Baird, A.N, Humburg, J, Pugh, D.G (1998) Surgical reduction of ileal impactions in the horse: 28 cases. ''Vet Surg'', 27(6):555-60.</ref><ref name="Hanson 2">Hanson, R.R, Schumacher, J, Humburg, J, Dunkerkley, S.C (1996) Medical treatment of horses with ileal impactions: 10 cases (1990-1994).  ''J Am Vet Med Assoc'', 208(6):898-900.</ref>  The shorter the duration of colic before surgical intervention, the better the prognosis.<ref>Embertson, R.M, Colahan, P.T, Brown, M.P, Peyton, L.C, Schneider, R.K, Granstedt, M.E (1985) Ileal impaction in the horse.  ''J Am Vet Med Assoc'', 186(6):570-2.</ref>  The requirement for enterotomy, enterectomy, jejunocecostomy during surgery<ref>Parks, A.H, Doran, A.E, White, N.A, Allen, D, Baxter, G.M (1989) Ileal impaction in the horse: 75 cases.  ''Cornell Vet'', 79(1):83-91.</ref> and the development of postoperative adhesions have all been associated with a poorer prognosis for survival.<ref name="Baxter">Baxter, G.M, Broome, T.E, Moore, J.N (1989) Abdominal adhesions after small intestinal surgery in the horse.  ''Vet Surg'', 18(6):409-14.</ref>

The prognosis for survival is generally good.<ref name="Hanson">Hanson, R.R, Wright, J.C, Schumacher, J, Baird, A.N, Humburg, J, Pugh, D.G (1998) Surgical reduction of ileal impactions in the horse: 28 cases. ''Vet Surg'', 27(6):555-60.</ref><ref name="Hanson 2">Hanson, R.R, Schumacher, J, Humburg, J, Dunkerkley, S.C (1996) Medical treatment of horses with ileal impactions: 10 cases (1990-1994).  ''J Am Vet Med Assoc'', 208(6):898-900.</ref>  The shorter the duration of colic before surgical intervention, the better the prognosis.<ref>Embertson, R.M, Colahan, P.T, Brown, M.P, Peyton, L.C, Schneider, R.K, Granstedt, M.E (1985) Ileal impaction in the horse.  ''J Am Vet Med Assoc'', 186(6):570-2.</ref>  The requirement for enterotomy, enterectomy, jejunocecostomy during surgery<ref>Parks, A.H, Doran, A.E, White, N.A, Allen, D, Baxter, G.M (1989) Ileal impaction in the horse: 75 cases.  ''Cornell Vet'', 79(1):83-91.</ref> and the development of postoperative adhesions have all been associated with a poorer prognosis for survival.<ref name="Baxter">Baxter, G.M, Broome, T.E, Moore, J.N (1989) Abdominal adhesions after small intestinal surgery in the horse.  ''Vet Surg'', 18(6):409-14.</ref>

==Prevention==

==Prevention==

*Adequate and appropriate feeding of good quality forage

*Adequate and appropriate feeding of good quality forage

*Avoidance of sudden dietary changes

*Avoidance of sudden dietary changes

Faceal worm egg counts do not reliably detect horses infected with ''A.perfoliata''.  An '''ELISA''' to test for the host antibody response to tapeworms has been developed with a reported sensitivity of 70% and a specificity of 95%.<ref>Proudman, C.J, Trees, A.J (1996) Use of excretory/secretory antigens for the serodiagnosis of ''Anoplocephala perfoliata'' cestodosis.  ''Vet Parasitol'', 61:239-247.</ref>  Although this test is useful for detecting horses with a high intensity of infection, it measures past and current infection so must be interpreted in light of the anthelmintic history.  More recently, a '''coproantigen capture ELISA''' has demonstrated some promise in a small sample of horses.<ref name="Kania">Kania, S.A, Reinemeyer, C.R (2005) ''Anoplocephala perfoliata'' coproantigen detection: a preliminary study. ''Vet Parasitol'', 127(2):115-9.</ref>  Such tests may be used as part of a '''targeted strategic dosing''' programme for anthelmintic administration.

Faceal worm egg counts do not reliably detect horses infected with ''A.perfoliata''.  An '''ELISA''' to test for the host antibody response to tapeworms has been developed with a reported sensitivity of 70% and a specificity of 95%.<ref>Proudman, C.J, Trees, A.J (1996) Use of excretory/secretory antigens for the serodiagnosis of ''Anoplocephala perfoliata'' cestodosis.  ''Vet Parasitol'', 61:239-247.</ref>  Although this test is useful for detecting horses with a high intensity of infection, it measures past and current infection so must be interpreted in light of the anthelmintic history.  More recently, a '''coproantigen capture ELISA''' has demonstrated some promise in a small sample of horses.<ref name="Kania">Kania, S.A, Reinemeyer, C.R (2005) ''Anoplocephala perfoliata'' coproantigen detection: a preliminary study. ''Vet Parasitol'', 127(2):115-9.</ref>  Such tests may be used as part of a '''targeted strategic dosing''' programme for anthelmintic administration.

==References==

==References==

<references/>

<references/>

[[Category:Intestine_-_Mechanical_Obstruction]]

[[Category:Intestine_-_Mechanical_Obstruction]]

[[Category:Surgical_Colic_in_the_Horse]]

[[Category:Surgical_Colic_in_the_Horse]]

[[Category:To_Do_-_Nina]]

[[Category:Expert_Review]]

[[Category:To_Do_-_Review]]

[[Category:Impaction - Horse]]

[[Category:Impaction - Horse]]

[[Category:Colic - Small Intestinal Causes]]

[[Category:Colic - Small Intestinal Causes]]

[[Category:Small Intestinal Disorders - Horse]]

[[Category:Small Intestinal Disorders - Horse]]