Chapter 18 Disorders of Hemostasis Hemostasis Unit 3 Chapter 18 Disorders of Hemostasis Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

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.

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.

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.

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.

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

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.

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, aPTT, ACT, and PIVKA May require several weeks of treatment Copyright © 2015 by Mosby, an imprint of Elsevier Inc. All rights reserved.

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.

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.