Bovis ISSN 2398-2993

Rumen impaction

Contributor(s): Ben Dustan , Neil Paton

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  • Cause: variable.
    • Typically dietary: excess fibrous diet with inadequate water supply, (low) protein forages. 
    • Some impactions can be secondary to pathologic disease processes, eg acute traumatic reticuloperitonitis/pericarditis, vagal indigestion etc.
    • Careful diagnostic discrimination is required to enable appropriate treatment.
  • Signs: abdominal distension, inappetance, depression, poor hair coat, abnormal/dry/reduced feces, cranial abdominal discomfort, reduced body condition score / reduced weight gain.
  • Diagnosis: history, clinical signs, clinical examination, rumenocentesis, rumenotomy/ exploratory laparotomy.
  • Treatment: dietary adjustment, supportive treatment, surgery/ treatment of underlying pathologic cause if present (rumenotomy / exploratory laparotomy).



  • The most common causative factors for ruminal impaction are the feeding of poor quality, low protein forage rations; or an abrupt change or alteration of the dietary ration.
  • Such a change can cause the rumen microflora to become inactive, or decrease in number so that digestive fermentation is reduced. 
  • This microbial inactivity diminishes the metabolic and fermentative processes within the rumen, which prolongs the breakdown of the ingested feedstuffs and leads to an increase in particulate matter size and prolonged retention of ingesta within the rumen. Rumen function
  • Increasing ingesta retention gradually distends the reticulorumen. This pathologic distension can weaken ruminal contractions and allow moderate tympany to develop (audible by auscultation).
  • Ruminal hypomotility alters normal ruminal ingesta stratification and fibrous components are found within ruminal fluid and become impacted ventrally, further obstructing ruminal outflow.
  • Reduced ruminal-reticular outflow results in a decrease in fecal volume and output. Rate of passage also slows so that feces become dry and contain undigested fibrous matter.
  • Prolonged anorexia reduces rumen fill over time with a resultant decrease in ruminal distension and ultimately rumen stasis develops.
  • Other factors which can result in this scenario include:
    • Grain over-eating.
    • Failure in water supply (frozen pipes, interrupted mains supply, broken trough).
    • Poor weaning / post-weaning dietary transition in calves.
    • Foreign body ingestion.


  • Typically days.
  • Specific impactions can be acute - for example grain overload, or chronic when the impaction is secondary to an underlying pathology for example Vagal indigestion Vagal indigestion or Traumatic reticuloperitonitis Traumatic reticuloperitonitis.


  • Dietary ruminal impactions usually affect whole groups / herd of animals (exception may be escaped individual to grain store).
  • Secondary ruminal impaction to an underlying pathologic condition usually affect an individual or small numbers of animals.


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Further Reading


Refereed Papers

  • Recent references from PubMed and VetMed Resource.
  • Anon (2016) Low protein silage associated with rumen impaction in suckler cows. Veterinary Record 178 (17), 413-16.
  • Tour A S & Saini N S (2008) Diagnostic and prognostic indicators of omasal impaction in buffaloes (Bubalus bubalis). Veterinary Record 162 (9), 275-77.
  • Blikslager A T, Anderson K L, Bristol D G, Fubini S L & Anderson D E (1995) Repeat laparotomy for gastrointestinal disorders in cattle: 57 cases (1968 - 1992). J Am Vet Med Assoc 207 (7), 939-43.
  • Ashcroft R A (1983) Abomasal impaction of cattle in Saskatchewan. Can Vet J 24 (12), 375-80.

Other sources of information

  • Andrews A H, Blowey R W, Boyd H, Eddy R G (2008) Diagnosis and differential diagnoses in the cow. In: Bovine Medicine. 2nd Edn. pp 140-41,145.
  • Andrews A H, Blowey R W, Boyd H & Eddy R G (2008) Digestive disorders of cattle. In: Bovine Medicine. 2nd Edn. pp 236.
  • Smith B P (2002) Diseases of the alimentary tract. In: Large Animal Internal Medicine. 3rd Edn. pp 731, 736-745.