Difference between revisions of "Coagulation Factor Deficiency"

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[[Category:Coagulation Defects]]
 
[[Category:Coagulation Defects]]
 
[[Category:Haemorrhagic Diseases]]
 
[[Category:Haemorrhagic Diseases]]
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[[Category:To Do - Blood]]

Revision as of 13:16, 11 August 2010

  • Factor deficiency
    • Often the result of a congenital deficiency in one or more of the coagulation factors.
    • Gives ineffective blood clotting and development of a disease syndrome characterized by excessive bleeding. S
      • Such bleeding is usually detected following trauma or surgery.
        • May occasionally be spontaneous (e.g. into alimentary or urinary tracts).
    • Often seen as familial inherited problems.
      • E.g. haemophilia


Diseases associated with coagulation factor defects

  • Most cases of "factor disease" in animals are similar to those studied in man.
    • Congenital.
    • Based on familial occurence.
    • Clotting biochemistry is similar in man and animals.
  • Most investigations have been carried out in the dog.
  • Haemophilia (factor VIII deficiency) is probably the best understood condition.

Von Willebrand's Disease

  • Seen in the dog.
    • Most common in Scottish Terriers and Chesapeake Bay Retrievers.
    • Has been seen more recently in Dobermanns, Setters and German Shepherd dogs.
    • A similar disease has been recorded in the pig.
  • Von Willebrand's Disease is an inherited autosomal recessive trait.
    • It is incompletely dominant, so there is variable expression.
  • Presentation
    • Purpura.
    • Prolonged bleeding time.
    • Reduced platelet adhesiveness.
    • Low Factor XIII levels.
  • The disease can be assessed by the measurement of Von Willebrand Factor protein levels.
    • A Factor VIII-related protein.
    • Synthesised in endothelial cells and megakaryocytes.
    • Stored in platelets.
    • Levels are low in affected animals.


Deficiency states of other factors have been recorded sporadically as follows:

Factor I

  • Factor 1 is fibrinogen.
  • Hyperfibrinogenaemia occurs in
    • Pregnancy
    • Acute infections
    • Post-operative states
    • Pyometra
  • Hypofibrinogenaemia is seen in
    • Liver disease.
    • Depletion by intravascular coagulation.

Factor II

  • Factor II is part of the prothrombin complex.
  • Hypoprothrombinaemia
    • A depression of the components of the prothrombin complex.
      • I.e. Factors II, VII, IX, X
    • May be caused by dicoumarol and its derivatives, for example sweet clover and warfarin.
      • Competitively inhibits Vitamin K in the liver, where the above Factors are synthesised.

Factor IV

  • Factor IV is calcium.
    • Necessary at several stages of coagulation.
  • Hypocalcaemia at a level sufficient to impair haemostasis is incompatible with life.
    • There is therefore no bleeding defect associated with hypocalcaemia.

Factor VII

  • Factor VII is Proconvertin.
  • Deficiencies do not appear to impair the formation of haemostatic plug.
    • The bleeding defect is normally mild.
  • Newborn pups have a very low plasma level of Factor VII.
    • Spontaneous and inherited deficiencies have been reported in Beagle colonies.
  • Deficiencies may also occur associated with liver disease and in dicoumarol poisoning.

Factor VIII

  • Factor VIII is known as antihaemophilic factor (AHF).
  • Deficiency of this factor causes haemophilia A.
    • The primary thrombocyte plug is abnormal.
      • More vascular channels than usual.
      • Less fibrin-collagen contact around the edges.
    • Plugs are therefore easily dislodged.
      • Results in rebleeding.
      • Secondary plugs only form with difficulty.
  • Haemophilia is reported in horses and in around 20 breeds of dogs.
  • Haemophilia is as a sex-linked recessive condition.
    • Associated with the X chromosome.
    • Affects males only.
  • The severity of the disease correlates with the Factor VIII levels.
  • Haematomas and haemarthrosis are common lesions.

Factor IX

  • Factor IX is Christmas Factor.
  • Deficiency causes haemophilia B.
    • Seen in Cairn Terriers and Black and Tan Hounds.
    • A sex-linked (X chromosome) recessive.
    • Results in a deficient haemostatic plug.
      • Similar to Factor VIII deficiency.

Factor XI

  • Factore XI is Plasma Thromboplastin Antecedent.
  • Deficiency has been reported in a cow, and reduced levels in the horse.

Factor XII

  • Factor XII is Hageman Factor.
  • Low plasma levels had been reported in cats and horses.