Platelet disorders

Question 1

What are the clinical signs of Thrombocytopenia?

Answer 1

• Petechiae and ecchymoses common
• Hematomas are rare
• Bleeding often involves mucus membranes
• Bleeding usually at multiple sites

Question 2

Why would patients have petechiae (bleeding)?

Answer 2

• Defect in vessels
• Defect in primary hemostasis
• Defect in secondary hemostasis

Question 3

How are Primary and secondary hemostatic disorders differentiated?

Answer 3

• Primary:
  
  • Most common: Petechiae, ecchymoses
  • Also: Epistaxis, hematuria, GI hemorrhage, prolonged wound bleeding
• Secondary:
  
  • Most common: Hematoma, hemarthrosis, hemoptysis
  • Also: Epistaxis, melena, hematochezia, hematemesis, prolonged hemorrhage

Question 4

How is Primary Hemostasis tested for?

Answer 4

• Buccal Mucosal Bleeding time
  
  • not a reliable indicator of vascular integrity
  • Prolonged with vWd and thrombopathy
• Von Willebrand’s factor Antigen assay
  
  • Important for certain reeds
• Platelet count

Question 5

How is Secondary Hemostasis tested for?

Answer 5

• Partial thromboplastin Time (PTT)
• Prothrombin time (PT)
• Proteins induced by vitamin K antagonists (PIVKA)
• Specific Clotting factor assays

Question 6

What are the general rules for thrombocytopenia?

Answer 6

• Platelet count <50,000 for bleeding
  
  • Often <30,000 in dogs
  • <10,000 in cats
• Severity helps predict disease
• presence of other diseases ⇢ DIC
• Bone marrow evaluation not helpful
• Primary autoimmune disease of cats is rare

Question 7

What causes thrombocytopenia?

Answer 7

• Decreased production (Bone Marrow disorder)
  
  • Drug-induced (Cytotoxic drugs, TMS, estrogen)
  • Myelofibrosis (Idiopathic, immune mediated)
  • Neoplasia (-phthisis, -dysplasia, -proliferative disease)
  • Infection (FeLV, FIV, Chronic ehrilichiosis)
• Increased Consumption
  
  • Immune-mediated thrombocytopenia (1^o, 2^o)
• Increased utilization
  
  • Disseminated Intravascular Coagulation
  • Hemorrhage
  • Vasculitis (acute, ehrlichiosis, immune, RMSF)

Question 8

What diagnostic tests are considered when diagnosing thrombocytopenia?

Answer 8

• Platelet indices (MPV): no support in aiding a diagnosis
• Coagulation panel, d-dimers: rule out DIC
• Tick-borne disease screening (4DX, serology, PCR)
• Radiographs, ultrasonography
• Immunological tests: PSA-Ig, ANA

Question 9

How is Immune-mediated Thrombocytopenia (ITP) diagnosed?

Answer 9

• Anti-platelet antibody testing
  
  • Flow cytometry
• Diagnosis of Exclusion
• Predicted by platelet count

Question 10

What is the presentation of Immune-mediated Thrombocytopenia?

Answer 10

• Bleeding (75%)
• Splenomegaly (60%)
• Platelet count <30,000 (80%), <8000 (50%)
• Anemia (40%) from blood loss
• 90% survival rate
• 25% recurrence rate

Question 11

What are the possible outcomes of Immune-mediated Thrombocytopenia?

Answer 11

• Recovery after a single event
• Recurrent
• Chronic ITP

Question 12

What are the treatment options for Immune-mediated thrombocytopenia?

Answer 12

• Blood product options:
  
  • Fresh Whole Blood/PRBC: used to correct anemia
  • Platelet-rich plasma: misnomer
• Immunosuppressive Therapy
  
  • Rapid Acting drugs
    
    • Prednisone: 2-4 mg/kg/day, inhibits uptake platelets
    • Vincristine: Paralyze RES or Forced maturation
    • Intravenous gamma globulin: Flood RES; anti-idiotypic Abs
  • Moderate acting: cyclosporine, leflunomide
  • Slow acting: Azathioprine, Mycophenolate

Question 13

What are causes of thrombocytopenia in cats?

Answer 13

• FeLV, FIV
• FIP
• Lymphoma/Leukemia
• Immune-mediated
• Histoplasmosis

Question 14

What is Disseminated Intravascular Coagulation (DIC)?

Answer 14

• Consequence/complication of other disease
• Paradox of thrombosis and hemorrhage
• Diagnosis:
  
  • Markedly increased D-dimer and FDPs
  • Prolonged APTT/PT
  • Thrombocytopenia
  • Schistocytes, reduced (fibrinogen)
• Treat underlying cause, FFP, heparin

Question 15

What is Systemic Lupus Erythematosus?

Answer 15

• Multi-organ autoimmune disease
• Variable symptoms/presentations
• Classic descriptions:
  
  • Major/Minor signs
  • ANA/LE prep
• Less rigid/stringent definitions
• Not all are positive on Anit-Nuclear Antibody (ANA)

Question 16

What are the signs of SLE?

Answer 16

• Fever: constant or cyclic
• Polyarthritis (nonerosive)
• Glomerulopathy
• Dermatologic lesions
• IMHA, ITP, Leukopenia
• Polymyositis, dermatomyositis, pleuritis/pericarditis, polyneuritis/CNS, hepatic disease, rhinitis, pneumonitis

Question 17

What laboratory Diagnostics are used for SLE?

Answer 17

• Anti-Nuclear Antibody
  
  • Positive in 97-100% of dogs
  • False positive occur
• Other tests not used in dogs:
  
  • LE prep test
  • ANti-histone antibodies
  • Anti-extractable nuclear antigen antibodies
  • Anti-SR protein antibodies

Question 18

What is the treatment for SLE?

Answer 18

Similar to IMHA or ITP

Question 19

What are Thrombotic Disorders?

Answer 19

• Occurs when conditions promote blood stasis, vascular injury and hypercoagulability
• Clinical manifestations
  
  • Acute paralysis
  • Dyspnea
  • Abdominal Pain
• Diagnostic tests
  
  • Determined by underlying condition
  • D-dimer, antithrombin, TEG

Question 20

What are the etiologies of Thromboembolic Disease

Answer 20

• Cardiac disease - HCM, DCM, CHF
• Corticosteroid therapy
• DIC
• Endocrine disease - Cushing’s, Hypothyroidism
• Heartworm disease
• Immunological disease - IMHA, SLE
• Neoplasia
• Acute Pancreatitis
• Protein-losing nephropathy
• Protein-losing enteropathy
• Trauma

Question 21

How is Thromboembolic Disease treated?

Answer 21

• Treat underlying disorder
• Clopidogrel