Impaction - Horse

Also known as:

Colic Impaction Simple Obstruction Mechanical Obstruction Functional Obstruction Oesophageal obstruction Choke Gastric Impaction Small Intestinal Simple Obstruction Ascarid Impaction Ileal Impaction Large Intestinal Simple Obstruction Caecal Impaction Colon Impaction Large Colon Impaction Pelvic Flexure Impaction Sand Impaction Small Colon Impaction Meconium Impaction

See also:

Colic in Horses Colic Diagnosis in Horses Medical Colic in the Horse Medical Treatment of Colic Surgical Colic in the Horse

Description

Impactions are simple obstructions of the gastrointestinal system. In the horse they include:

• Oesophageal obstruction ('choke')
• Gastric impaction
• Small intestinal simple obstruction
  • Ascarid impaction
  • Ileal impaction
• Large intestinal simple obstruction
  • Caecal impaction
  • Large colon impaction
  • Sand impaction
  • Small colon impaction
  • Meconium impaction

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 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 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