part 1.3 hemostasis disorders

What are the main categories of hemostasis disorders

Vessel wall defects, thrombocytopenia, thrombocytosis, platelet function defects, coagulation factor deficiency (acquired and hereditary), and disseminated intravascular coagulation (DIC).

What are vessel wall defects

Collagen deficiency that weakens vessel integrity and predisposes to hemorrhage.

What other condition causes vessel wall damage and bleeding

Disseminated intravascular coagulation (DIC) due to endothelial injury and widespread microthrombosis.

What is thrombocytopenia

An abnormal reduction in circulating platelet count.

What are the clinical signs of thrombocytopenia

Petechiae and ecchymoses, which are hallmarks of severe thrombocytopenia.

What are the causes of thrombocytopenia

Abnormal platelet production due to bone marrow disorders (↓ megakaryopoiesis), excessive platelet consumption in hemostatic processes, and platelet destruction (often immune-mediated).

What is pseudothrombocytopenia

A false decrease in platelet count caused by platelet clumping in the sample.

What is thrombocytosis

An increased platelet count in the blood.

What are the causes of thrombocytosis

Neoplastic (primary) and reactive (secondary) causes.

What is primary thrombocytosis

Bone marrow neoplasia (e.g., hemic neoplasia) leading to increased platelet production.

What are reactive causes of thrombocytosis

Redistribution due to splenic contraction, exercise, or epinephrine, and increased production driven by inflammation (cytokine-mediated).

What are platelet function defects

Conditions where platelet count is normal but platelet function is abnormal.

What are the two types of platelet function defects

Acquired and hereditary.

What are examples of acquired platelet function defects

Drug effects such as aspirin inhibiting platelet cyclooxygenase (↓ thromboxane A2 → impaired aggregation) and DIC syndrome where widespread coagulation activation consumes platelets and disrupts their function.

What is the main hereditary platelet function defect

Von Willebrand’s Disease (vWD).

What causes von Willebrand’s Disease

Deficiency or abnormality of von Willebrand factor (vWF) leading to impaired platelet adhesion, often accompanied by secondary Factor VIII deficiency.

What are the three types of von Willebrand’s Disease

Type 1, Type 2, and Type 3.

Describe Type 1 von Willebrand’s Disease

All vWF multimers are present but decreased in concentration; common in Doberman pinschers.

Describe Type 2 von Willebrand’s Disease

Deficiency of vWF with a disproportionate decrease in large multimers; common in German shorthaired and German wirehaired pointers.

Describe Type 3 von Willebrand’s Disease

Absence of all vWF multimers; reported in Chesapeake Bay Retrievers, Dutch Kooikers, Scottish Terriers, and Shetland Sheepdogs.

What are acquired coagulation deficiencies

Conditions that cause reduced production or activity of clotting factors.

What are the two main types of acquired coagulation deficiency

Diminished production and factor inhibition.

What causes diminished production of coagulation factors

Vitamin K deficiency and liver disease.

What causes Vitamin K deficiency

Antimicrobial-induced gut sterilization and malabsorption.

What does Vitamin K deficiency lead to

Reduced activity of Vitamin K–dependent factors II, VII, IX, and X.

How does liver disease cause coagulation deficiency

Impaired synthesis of clotting proteins and defective clearance of procoagulants, anticoagulants, and fibrinolytic regulators.

What causes factor inhibition

Heparin therapy and DIC syndrome.

How does heparin therapy inhibit coagulation

Potentiates antithrombin, inhibiting thrombin and Factor Xa.

How does DIC cause coagulation deficiency

Consumption and inactivation of multiple clotting factors.

What are hereditary coagulation factor deficiencies

Genetic defects resulting in reduced or absent clotting factor activity.

What is Hemophilia A

Factor VIII deficiency.

What is Hemophilia B

Factor IX deficiency (also called Christmas disease).

What type of inheritance do Hemophilia A and B follow

X-linked recessive.

Which sexes are affected by X-linked hemophilia

Males are affected if the gene is present; females are usually carriers and rarely affected.

What are the possible outcomes of a carrier female × normal male cross

50% carrier females and 50% affected males.

What are the possible outcomes of a carrier female × affected male cross

Carrier females, affected females possible, and affected males.

What are the outcomes of an affected male × normal female cross

All females are carriers and all males are normal.

What is Hemophilia C

Factor XI deficiency.

What type of inheritance does Hemophilia C have

Autosomal inheritance; both sexes equally affected.

What is Factor X deficiency

A coagulation defect that is severe in neonates (mimics fading puppy syndrome) and mild to severe in adults.

Which breeds are affected by Factor X deficiency

American Cocker Spaniels and Jack Russell Terriers.

What is Factor VII deficiency

Usually mild with easy bruising and prolonged clotting time; reported in Beagles.

What are fibrinogen disorders

Factor I deficiencies involving abnormal fibrinogen quantity or quality.

What are the three forms of fibrinogen disorders

Afibrinogenemia (absence), hypofibrinogenemia (reduced), and dysfibrinogenemia (abnormal fibrinogen).

How severe is bleeding in fibrinogen disorders

It ranges from mild to severe.