Abomasal impaction

Etiology

• Primary disorder:
  • Impaction occurs following abomasal hypomotility.
  • Pathogenesis the same for an LDA Left Displaced Abomasum.
• Dietary impaction:
  • Impaction with poor quality roughage.
    • Most commonly occurs in young, pregnant beef animals fed poor quality roughage during periods of cold weather.
    • Increased risk if the roughage is provided at a short cut length as intakes are higher and there is a quicker transit time to the abomasum. 
  • Impaction with or sand/gravel.
    • If poor grazing is on sandy soil, or sand is inadvertently included in ration or pica. 
  • Impaction secondary to luminal foreign body, eg plastic bags, twine or phytobezoars.
• Secondary to other conditions such as:
  • Traumatic reticuloperitonitis Traumatic reticulitis.
  • Vagal indigestion Vagal indigestion.
  • Lymphosarcoma.
• Can occur in calves if:
  • Large quantities of bedding are eaten, usually associated with poor quality milk replacer.
  • Large amounts of hair are ingested (trichobezoar) due to excessive licking.

Predisposing factors

Pathophysiology

• Impaction can affect the abomasal body, the pyloric antrum or both. 
• Following impaction and abomasal atony, hypochloremia, hypokalemia Potassium, and metabolic alkalosis Acid base can develop.

Timecourse

• Usually chronic with condition loss noted over 1-2 weeks. 
• If a severe case then can lead to abomasal rupture and acute peritonitis. Severe cases will result in death in 3-6 days after the first clinical signs. 
• Sand impactions can be more insidious and cause a steady deterioration over several weeks.

Epidemiology

• Primary disorder – periparturient dairy cattle, can occur sporadically or due to change in transition cow management Nutritional requirements of high yielding dairy cows.
• Dietary impaction:
  • Outbreaks can occur due to shared risk factors such as increased intakes due to cold weather or pregnancy combined with poor quality roughage.
• Acute septic peritonitis can occur if abomasum ruptures.