Difference between revisions of "Impaction - Horse"

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#REDIRECT[[:Category:Impaction - Horse]]
 
 
{| cellpadding="10" cellspacing="0" border="1"
 
| Also known as:
 
|'''Colic<br>
 
'''Impaction<br>
 
'''Simple Obstruction<br>
 
'''Mechanical Obstruction<br>
 
'''Large Intestinal Simple Obstruction<br>
 
'''Colon Impaction<br>
 
'''Large Colon Impaction<br>
 
'''Small Colon Impaction<br>
 
'''Pelvic Flexure Impaction<br>
 
'''Caecal Impaction<br>
 
'''Small Intestinal Simple Obstruction<br>
 
'''Ascarid Impaction<br>
 
'''Ileal Impaction<br>
 
'''Sand Impaction'''
 
|}
 
 
 
{| cellpadding="10" cellspacing="0" border="1"
 
| See also:
 
|'''[[:Category:Colic Diagnosis in the Horse|Colic Diagnosis in Horses]]<br>
 
'''[[:Category:Medical Colic in the Horse|Medical Colic in the Horse]]<br>
 
'''[[:Category:Surgical Colic in the Horse|Surgical Colic in the Horse]]<br>
 
'''[[Colic, Medical Treatment|Medical Treatment of Colic]]<br>
 
'''[[Colic, Decision Making|Decision Making in Colic]]<br>
 
'''[[Colic, Gastric Causes]]<br>
 
'''[[Colic, Small Colon Causes]]'''
 
|}
 
 
 
 
 
 
==Description==
 
 
 
Impactions are simple obstructions of the gastrointestinal system.  They include:
 
*[[Ileal Impaction - Horse|Ileal impaction]]
 
*[[Caecal Impaction - Horse|Caecal impaction]]
 
*[[Large Colon Impaction - Horse|Large colon impaction]]
 
*[[Small Colon Impaction - Horse|Small colon impaction]]
 
*[[Sand Impaction - Horse|Sand impaction]]
 
 
 
==Prevalence==
 
==Signalment==
 
 
 
==Pathophysiology==
 
 
 
===Anatomy===
 
Impactions of the large colon occur where the luminal diameter narrows, especially the pelvic flexure and the right dorsal colon (RDC) (83 in Bliks).  Food impactions occur most often at the pelvic flexure, the site of the myoelectrical pacemaker.  Sand impactions occur at various sites in the large intestine.
 
 
 
===Risk Factors===
 
 
 
Sudden restriction in exercise associated with musculoskeletal injury (84)
 
Twice daily feeding of concentrate - large fluxes of fluid into and out of colon, associated with readily fermentable carbohydrate in the colon and increases in serum aldosterone.  Fluid fluxes may cause dehydration of ingesta during aldosterone-stimulated net fluid flux out of the colon (32).
 
Amitraz - acaricide associated with clinical cases of colon impaction (85,86) - may alter pelvic flexure pacemaker activity resulting in uncoordinated motility patterns between the left ventral and left dorsal colon and excessive retention of ingesta.  Absorption of water from ingesta increases with time, dehydrating the contents of the colon and resulting in impaction
 
Parasite migration in the region of the pacemaker (87)
 
Limited exercise
 
Poor dentition
 
Coarse roughage
 
Dehydration
 
 
 
 
 
==Clinical Signs==
 
 
 
Slwo onset mild colic
 
Reduced defaecation
 
Faeces hard, dry and mucus-covered because of delaed transit
 
Heart rate mildly elevated during painful episodes but often normal
 
Colic signs typically well controlled with analgesics but become increasingly more severe and refractory if impaction not resolved
 
 
 
 
 
 
 
 
 
 
 
==Diagnosis==
 
 
 
See <big>[[:Category:Colic Diagnosis in the Horse|Colic Diagnosis in Horses]]
 
===Rectal examination===
 
 
 
Firm mass in large colon but may underestimate extent of impaction because much of colon out of reach (83).  Adjacent colon may be distended if impaction has resulted in complete obstruction.  Impaction at other sites such as the transverse colon may not be palpable per rectum.
 
 
 
==Treatment==
 
 
 
 
 
 
 
===Medical===
 
See [[Colic, Medical Treatment|Medical Treatment of Colic in Horses]].
 
*Initially intermittent abdominal pain controlled with analgesics:
 
**Flunixin meglumine 0.25-1.1mg/kg IV every 6-12 hours
 
**Butorphanol 0.05-0.1 mg/kg IV every 6-8 hours
 
**Xylazine 0.3-0.5mg/kg IV as needed
 
*Oral laxatives to soften the impaction:
 
**Liquid paraffin or mineral oil 2-4lites by nasogastric tube every 12 to 24 hours
 
**Anionic surfactant dioctyl sodium succinate (DSS) 6-12g/500kg diluted in 2-4litres of water by nasogastric tube every 12-24 hours
 
*Saline cathartics such as magnesium sulphate 0.1 mg/kg in 2-4litres by nasgastric tube may also be useful
 
*Prevent access to feed
 
Aggressive oral and IV fluid therapy (2-4 times maintenance) if impactions persist(83)
 
 
 
===Surgical===
 
 
 
If impaction remains unresolved, pain becomes uncontrollable, or extensive gas distension of the colon occurs, surgery is indicated.  Abodominocentesis can be used to monitor the onset of intestinal compromise.(83)  At surgery the contents of the colon are evacuated via a pelvic flexure enterotomy.
 
 
 
 
 
==Prognosis==
 
 
 
Good for impactions that resolve medically (95% long term survival in one study) and fair in horses that require surgical intervention (58% long-term survival in the same study) (84)
 
 
 
==Prevention==
 
 
 
Frequent small feedings(32)
 
 
 
==References==
 
<references/>
 
[[Category:Intestine_-_Mechanical_Obstruction]]
 
[[Category:Medical_Colic_in_the_Horse]]
 
[[Category:To_Do_-_Nina]]
 

Latest revision as of 21:51, 6 October 2010