Introduction

• Cause: perforation of the reticulum, usually by a sharp metallic object, such as a wire.
• Signs: GI stasis, thoracic or abdominal pain, reduced milk yield.
• Diagnosis: ultrasound of the cranioventral abdomen, rumenotomy.
• Treatment: insertion of reticular magnet, rumenotomy, antibiotics and NSAIDs.
• Prognosis: guarded - depends on extent of object penetration.

Pathogenesis

Etiology

• Sharp metal objects, typically wire (from the inner wall of tyres ) or nails, are ingested by the cow.
• Can occur as cows do not completely masticate their food before swallowing.
• The object either falls directly into the reticulum after ingestion, or is pushed into the reticulum by ruminal contractions.
• The object doesn’t pass out of the reticulum as the reticulo-omasal opening is not at the most distal point, and objects get trapped in the honeycomb structure.
• The object penetrates the reticulum wall due to reticular contractions leading to leakage of bacteria and ingesta.
• Peritonitis develops producing reticular abscesses and adhesions.
• The object may penetrate the diaphragm and enter the lung:
  • Lung abscess.
  • Pleuritis.
• The object may penetrate the pericardium:
  • Pericarditis Heart: pericarditis.
  • Laceration of coronary artery - cardiac tamponade Cardiac tamponade.
• The object may occasionally penetrate the liver or spleen:
  • Abscessation.
  • Septicemia.

Pathophysiology

• Initial penetration of the reticulum, or breakdown of existing adhesions around an object allowing further movement can occur due to:
  • Compression of the ruminoreticulum by the uterus in late pregnancy.
  • Straining during parturition.
  • Mounting during estrus.
• Initial acute peritonitis can be followed by chronic local peritonitis with localized adhesions
  • This can present as cows just having vague signs of ill health with poor production.
• Rarely, diffuse generalized peritonitis can occur, especially following breakdown of previously formed adhesions.

Timecourse

• Generally acute disease over 24 hours.
• Possible to have more vague signs of ill health with chronic disease processes.

Epidemiology

• Generally individual animals affected, but can get herd outbreaks - for example, if a whole tyre is accidentally chopped up in the feed wagon.

Diagnosis

Treatment

Prevention

Outcomes