Haemorrhagic Diseases

Haemorrhagic Diseases

1. Increased Vascular Fragility

   • Non- Thrombocytopenic purpura
   • 1) Capillary Damage
     • Bacterial Toxins
       • Ex. Septicemia
   • 2) Chemical or Drug - Induced
     • Heavy metals, Pesticides, Salicylate (Aspirin)
   • 3) Anaphylaxis or Allergy
   • 4) Connective Tissue Disease
     • Ehlers - Danlos syndrome
     • Effects connective tissue of Endothelial walls

2. Inadequate Haemostatic response

   • Thrombocyte Deficiency or Dysfunction
     • Primary Thrombocytopenia Purpura
       • Secondary Thrombocytopenia Purpura
     • Thrombocytopenia
       • A) Decreased platelet production
         • Ex. Bone marrow disease
           • Bone marrow depleted of Megakaryocytes results in reduced platelets in blood
           • May be Pancytopenia if all cell lines affected
           • Diseases that depress bone marrow functions:
             • Severe viral/bacteria/protozoal infections
             • Plant toxicity
             • Neoplasia
       • B) Increased platelet destruction/utilization
         • Usually idiopathic
         • May be immune mediated
           • Primary Immune mediated thrombocytopenia
             • Ab directed at Megakaryocytes
           • Secondary Immune mediated thrombocytopenia
             • FIV, FeLV
         • Non-Immune mediated
           • DIC, Vasculitis
         • Bone marrow may show Megakaryocyte hyperplasia
           • Regeneration
       • C) Platelet sequestration
         • Usually only causes mild thrombocytopenia
     • Thrombopathias
   • Clotting Factor Deficiency or Derangement
     • Usually Familial & Congenital
       • Haemophilia A - Factor VIII deficiency
       • Von Willebrand's Disease (Factor VIII related protein)
         • 3 types (Dogs)
         • Results in poor platelet Rxn with Endothelial cells
     • Most commonly identified in dogs and cats
     • Aquired Coagulopathies
       • Vitamin K antagonism (Co-factor for some enzymes involved in coagulation)
         • Coumarin rodenticides
         • Some plants
           • Mouldy Melilotus
       • Vitamin K Deficiency
         • Secondary to maldigestion or malabsorption
       • Liver failure
         • Lack of production of coagulation factors