Platelet Disorders

Question 1

CCM 3rd Edition

Answer 1

Platelet Disorders

Question 2

How may thrombocytopenia develop

Answer 2

decreased production
increased destruction
increased consumption
sequestration

Question 3

How thrombocytopenic do animals have to be to spontaneously bleed

Answer 3

Usually below 30
Severe when below 10

Question 4

What is the proposed mechanism of ITP?

Answer 4

increased platelet phagocytosis by splenic macrophages due to autoantibodies bound to platelet integrin A2bB3 (fibrinogen receptor) or glycoprotein 1b-IX (vWB factor receptor)

Question 5

What causes thrombocytopenia in sepsis

Answer 5

multifactorial but may be the result of
increased platelet consumption due to direct microbial–platelet interactions (such as TLR4),
platelet–leukocyte aggregate formation,
increased platelet sequestration secondary to microvascular thrombosis

Question 6

What are the most common clinical signs of thrombocytopenia?

Answer 6

mucocutaneous bleeding, ecchymosis, petechiae, GI bleeding, hyphema

Question 7

What are potential causes of Acquired Thrombocytopenia in small animals

Answer 7

Increased consumption
-Disseminated intravascular coagulation
-Acute/severe blood loss
-Platelet activation/aggregation
-Sepsis
-Thrombotic microangiopathies
-Massive thrombosis
Iatrogenic
-Hemodialysis
-Postcardiopulmonary bypass
-Hemodilution including massive transfusion
-EDTA-mediated
Increased destruction
-Primary immune mediated thrombocytopenia
-Secondary immune mediated thrombocytopenia
* Anaplasmosis
* Babesiosis
* Ehrlichiosis
* Neoplasia
Decreased production
-Bone marrow disease
-Chemotherapy
Increased sequestration
-Splenic sequestration
-Sepsis/systemic inflammatory response syndrome

Question 8

What causes uraemia-induced thrombopathia?

Answer 8

multifactorial, we don’t really know - potentially compromised plt adhesion. thought to be associated with vWF dysfunction
They have enough vWF but it just ain’t workin

Question 9

What causes thrombocytopenia in liver disease?

Answer 9

no one know

Question 10

What drugs may affect plt function

Answer 10

anti-plt drugs
NSAIDs
PDEs
NO drugs
Heparin and Xa inhibitors
Fibrinolytics
Beta-lactams
Colloids

Question 11

congenital plt disorders

Answer 11

Glanzmann thrombasthenia
Scott syndrome
etc

Question 12

How to diagnose plt disorders?

Answer 12

1. Blood smear, CBC, Hx of bleeding, co-ags, fibrinogen, vWF measures, vWF antigen
2. BMBT, plt aggregometry
3. Flow cytometry, whole genome sequencing

Question 13

What recommendations surround patients on antiplt drugs having elective Sx

Answer 13

In patients at high risk of thrombosis, abrupt discontinuation of antiplatelet therapy prior to elective procedures is not recommended due to the potential rebound of platelet reactivity and acute thrombotic events. Discontinuation of one antiplatelet drug (preferably clopidogrel) 5 to 7 days prior to elective procedures is recommended in patients considered high risk of surgical bleeding receiving dual antiplatelet therapy.49 Antiplatelet drugs should be discontinued at least 5 to 7 days prior to elective procedures in animals with low to moderate risk of bleeding

Question 14

Treatment of plt disorders

Answer 14

boring - give them what they need