Coagulation Factor Deficiency

• 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.