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** Often seen as familial inherited problems.
 
** Often seen as familial inherited problems.
 
*** E.g. haemophilia
 
*** E.g. haemophilia
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===Diseases associated with coagulation factor defects===
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* Most cases of "factor disease" in animals are similar to those studied in man.
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** Congenital.
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** Based on familial occurence.
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** Clotting biochemistry is similar in man and animals.
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* Most investigations have been carried out in the dog.
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* [[Haemostasis - Pathology#Factor VIII|Haemophilia]] (factor VIII deficiency) is probably the best understood condition.
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====Von Willebrand's Disease====
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* Seen in the dog.
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** Most common in Scottish Terriers and Chesapeake Bay Retrievers.
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** Has been seen more recently in Dobermanns, Setters and German Shepherd dogs. 
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** A similar disease has been recorded in the pig. 
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* Von Willebrand's Disease is an inherited autosomal recessive trait.
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** It is incompletely dominant, so there is variable expression.
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* '''Presentation'''
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** Purpura.
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** Prolonged bleeding time.
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** Reduced platelet adhesiveness.
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** Low Factor XIII levels.
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* The disease can be assessed by the measurement of Von Willebrand Factor protein levels.
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** A Factor VIII-related protein.
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** Synthesised in endothelial cells and megakaryocytes.
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** Stored in platelets. 
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** Levels are low in affected animals.
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'''Deficiency states of other factors have been recorded sporadically as follows:'''
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====Factor I ====
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* Factor 1 is fibrinogen.
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* '''Hyperfibrinogenaemia''' occurs in
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** Pregnancy
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** Acute infections
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** Post-operative states
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** Pyometra
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* '''Hypofibrinogenaemia''' is seen in
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** Liver disease.
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** Depletion by intravascular coagulation.
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====Factor II ====
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* Factor II is part of the prothrombin complex.
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* '''Hypoprothrombinaemia'''
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** A depression of the components of the prothrombin complex.
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*** I.e. Factors II, VII, IX, X
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** May be caused by dicoumarol and its derivatives, for example sweet clover and warfarin.
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*** Competitively inhibits Vitamin K  in the liver, where the above Factors are synthesised.
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====Factor IV ====
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* Factor IV is calcium.
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** Necessary at several stages of coagulation. 
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* '''Hypocalcaemia''' at a level sufficient to impair haemostasis is incompatible with life.
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** There is therefore no bleeding defect associated with hypocalcaemia.
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====Factor VII====
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* Factor VII is Proconvertin.
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* Deficiencies do not appear to impair the formation of haemostatic plug.
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** The bleeding defect is normally mild.
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* Newborn pups have a very low plasma level of Factor VII.
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** Spontaneous and inherited deficiencies have been reported in Beagle colonies.
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* Deficiencies may also occur associated with [[Liver - Anatomy & Physiology|liver]] disease and in dicoumarol poisoning.
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====Factor VIII ====
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* Factor VIII is known as antihaemophilic factor (AHF).
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* Deficiency of this factor causes '''haemophilia A'''.
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** The primary thrombocyte plug is abnormal.
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*** More vascular channels than usual.
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*** Less fibrin-collagen contact around the edges. 
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** Plugs are therefore easily dislodged.
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*** Results in rebleeding.
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*** Secondary plugs only form with difficulty. 
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* Haemophilia is reported in horses and in around 20 breeds of dogs.
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* Haemophilia is as a sex-linked recessive condition.
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** Associated with the X chromosome.
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** Affects males only.
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* The severity of the disease correlates with the Factor VIII levels.
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* Haematomas and haemarthrosis are common lesions.
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====Factor IX ====
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* Factor IX is Christmas Factor.
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* Deficiency causes '''haemophilia B'''.
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** Seen in Cairn Terriers and Black and Tan Hounds.
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** A sex-linked (X chromosome) recessive.
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** Results in a deficient haemostatic plug.
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*** Similar to Factor VIII deficiency.
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====Factor XI====
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* Factore XI is Plasma Thromboplastin Antecedent.
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* Deficiency has been reported in a cow, and reduced levels in the horse.
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====Factor XII====
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* Factor XII is Hageman Factor.
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* Low plasma levels had been reported in cats and horses.
    
[[Category:Coagulation Defects]]
 
[[Category:Coagulation Defects]]
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[[Category:Haemorrhagic Diseases]]
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