Category:Forestomach - Nutritional Pathology

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Bloat


Rumenal Acidosis

  • Like bloat, rumenal acidosis is associated with mismanagement of feeding and involves cessation or depression of rumenal movements with development of a degree of tympany.
  • More common in cattle and goats than in sheep due to differences in diet.

Clinical

  • Animals display signs of abdominal discomfort, but usually recover if treated.
  • Acute disease can result in death if acidosis is severe.

Pathogenesis

  • Occurs following feeding of highly fermentable material, usually carbohydrate, in the form of concentrate or cereal
    • e.g. in barley beef feeding systems.
  • An overgrowth of Gram positive bacteria results, breaking carbohydrate down very quickly.
    • Increased volatile fatty acid production decreases the rumen pH to about 5.
      • Rumen epithelium is damaged- ruminitis.
      • Osmotic effects of rumen contents produce severe dehydration.
      • Death may ensue when the rumen pH drops to 4.5 or below.
  • Normal flora may invade the damaged wall of rumen e.g. Fusiformis necrophorum.
    • Results in areas with mushy necrotic papillae.
    • Especially on pillars and ventral parts of rumen.
  • Excess gas production may occur
    • Concentrate does not contain soluble proteins, therefore foam does not develop.
    • Only mild to moderate free gas bloat is likely- much of the rumenal distension which occurs with rumenal acidosis is due to fluid sequestration in the rumen.

Pathology

Gross

  • Gross PM findings may be non-specific.
  • Ruminal stasis/bloat leads to rumen distension
  • Rumen contents are porridge-like.
  • Rumenitis may be present
    • Normal flora invading wall of rumen may enter blood as thromboemboli and travel in the portal flow to liver
    • Focal abscesses are produced, which heal with sunken star-shaped scars.
  • Overgrowth of Clostridia may cause endotoxic shock with widespread petechial haemorrhages.

Histological

  • Microvesicles may be present in the epithelium of the rumen papillae.
  • May be focal erosions/ulceration.

Sequelae

  • Scarring- necrotised papillae are replaced by smooth epithelium closely adherent to sub mucosa.
  • Has economic significance since many barley beef livers are condemned at meat inspection.
  • More persistent organisms can invade rumen wall producing chronic infection.

Pages in category "Forestomach - Nutritional Pathology"

The following 2 pages are in this category, out of 2 total.