Hemostasis Unit 3 Chapter 18 Disorders of Hemostasis

Hemostatic Defects • Bleeding disorders may be caused by: • Congenital defects • Acquired

Clinical Signs • Congenital or acquired defects • • • Superficial petechia Ecchymotic hemorrhage

Hereditary Coagulation Factor Disorders • • • Include a variety of factor deficiencies Hemophilia

von Willebrand Disease • Most common inherited coagulation disorder of domestic animals • Decrease

von Willebrand Disease (cont. ) • Distinct forms based on patterns of inheritance •

Acquired Coagulation Disorder • Thrombocytopenia • Decreased number of platelets • Most commonly seen

Acquired Coagulation Disorder (cont. ) • Vitamin K deficiency • • • Required for

Acquired Coagulation Disorder (cont. ) • Disseminated intravascular coagulation • Not a disease on

Summary • Bleeding disorders caused by: • Congenital • Acquired • • • Clinical

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Hemostatic Defects • Bleeding disorders may be caused by: • Congenital defects • Acquired defects • Most disorders are secondary to another disease process • Primary coagulation disorders • Result of congenital defects Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 2

Clinical Signs • Congenital or acquired defects • • • Superficial petechia Ecchymotic hemorrhage Epistaxis Melena Prolonged bleeding • Injection sites or incisions • Function defects or deficiencies • Usually appear before animal is 6 months old Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 3

Hereditary Coagulation Factor Disorders • • • Include a variety of factor deficiencies Hemophilia A – most common inherited in dogs, caused by Factor VIII deficiency Hemophilia D (Christmas disease) – Factor IX deficiency Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 4

von Willebrand Disease • Most common inherited coagulation disorder of domestic animals • Decrease in von Willebrand factor • A large glycoprotein that circulates with Factor VIII and aids in platelet aggregation at the beginning of the coagulation pathway • Dobermans and other canines, rabbits, and swine Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 5

von Willebrand Disease (cont. ) • Distinct forms based on patterns of inheritance • Type 1 • Autosomal dominant inheritance pattern • Low levels of circulating v. WF with normal structure • Type 2 • Low levels of circulating v. WF with abnormal structure • Type 3 • Near absence of v. WF • Type 2 and 3 – most severe bleeding Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 6

Acquired Coagulation Disorder • Thrombocytopenia • Decreased number of platelets • Most commonly seen in veterinary practices • Cause often unknown • • Viral Bacterial Parasitic Medications • Aspirin • Acetaminophen Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 7

Acquired Coagulation Disorder (cont. ) • Vitamin K deficiency • • • Required for synthesis and activation of Factors II, VII, IX, and X Can be dietary or bile duct obstruction Ingestion of rodenticides or moldy sweet clover • Signs may take days to appear • • Lethargy, anorexia, dyspnea, ecchymosis, petechia, and hemarthrosis may occur Tests • PT, a. PTT, ACT, and PIVKA • May require several weeks of treatment Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 8

Acquired Coagulation Disorder (cont. ) • Disseminated intravascular coagulation • Not a disease on its own, but associated with many pathologic conditions • • • Trauma Septicemia Viruses Parasites Pancreatitis GDV Toxins Systemic hemorrhages or microvascular thrombosis Tests • No single test Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 9

Summary • Bleeding disorders caused by: • Congenital • Acquired • • • Clinical signs of bleeding disorders von Willebrand disease Thrombocytopenia Vitamin K deficiency DIC Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved. 10