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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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| − |
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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.
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| | [[Category:Haemostasis - Pathology]] | | [[Category:Haemostasis - Pathology]] |