Difference between revisions of "Bloat"

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| '''Tympany<br>
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| '''Ruminal tympany<br>
 
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Revision as of 10:39, 26 July 2010



Description

Signalment

Diagnosis

Clinical signs

Treatment

Prognosis

References

  • When eructation fails, the rumen becomes distended due to the accumulation of gas produced by the fermentation process. This distension is known as bloat or tympany.

Clinical

  • The disease is acute and progressive and will result in death in a matter of hours.

Pathology

  • In severe bloating, that the rumen almost fills the abdomen.
    • Diaphragm is displaced forwards, compressing the lungs.
    • Posterior vena cava (lying dorsally) is also compressed, reducing the venous return to the heart.
    • Respiration is depressed and animals die from anoxia.
      Oesophageal "bloat line" (Courtesy of Elspeth Milne)
      • Blood is dark (hypoxic) and clots poorly.
  • The anterior parts of the body are often characteristically acutely congested.
    • Oedema and subcutaneous haemorrhage of head and neck tissues.
    • Oesophageal "bloat line" at thoracic inlet.
      • Congested and haemorrhagic cranially, pale caudally.

Pathogenesis

  • There are two forms of bloat:
    • Frothy bloat/ Primary bloat
      • Occurs following ingestion of large amounts of succulent green plant material. This is highly fermentable and produces large amounts of gas.
      • Material contains high levels of soluble proteins. These act as foaming agents by reducing surface tension but increasing surface viscosity of rumenal liquids and a stable rumenal foam forms.
      • The volatile fatty acids of the plant material consumed lower pH, optimising conditions for formation of froth.
      • Gas present in bubble form is insufficient to trigger eructation, and so the rumen becomes distended.
    • Free gas bloat/ Secondary bloat
      • May be:
        • Acute
          • Due to sudden oesophageal obstruction, for example by a solid foreign body (e.g. a piece of potato or turnip).
        • Chronic
          • Results from partial oesophageal obstruction/ compression, or from interference with the normal eructation mechanism, e.g. with:
          • Some passage of gas is possible, so gas build-up and distenesion is more prolonged.
          • Interference with cardiac and respiratory function is seldom life threatening.
Also known as: Ruminal tympany