IMTP

Question 1

What occurs during primary hemostasis?

Answer 1

Formation of a platelet plug via PLT adhesion (vWF), activation, and aggregation

Question 2

What occurs during secondary hemostasis?

Answer 2

Coagulation factors are activated to produce end product of Fibrin that stabilizes the platelet plug formed during primary hemostasis

Question 3

What coagulation factors are measured using PT?

Answer 3

Factor 7 (extrinsic pathway)

Question 4

What coagulation factors are measured using aPTT?

Answer 4

12, 11, 9, 8 (intrinsic pathway)

Question 5

What clinical signs can be seen if there is an issue with primary hemostasis?

Answer 5

• Petechia
• Ecchymosis
• Oozing blood from mucosal sites (mouth, eyes, GI tract, nose, bladder)

Question 6

What clinical signs can be seen if there is an issue with secondary hemostasis?

Answer 6

• Bleeding into a body cavity
• Large SQ hematomas
• Larger scale blood loss that isn’t normally seen with primary hemostatic disorders

Question 7

What diagnostics are used to assess primary hemostasis?

Answer 7

• Manual blood smear to assess PLT count and R/O clumping
• Low or normal PLTs on CBC
• BMBT to assess PLT function (will be increased)

Question 8

What does an increased BMBT indicate?

Answer 8

• Primary hemostatic disorder
• Either a problem with PLT function or PLT numbers
• Consistent with marked thrombocytopenia

Question 9

List the most common differentials for thrombocytopenia

Answer 9

• IMTP (severe thrombocytopenia)
• Bone marrow disease (neoplasia, drugs)
• Pseudothrombocytopenia (Cavaliers, Greyhounds)
• Sequestration from splenomegaly
• DIC (consumption)
• Bleeding / Blood loss (less likely to cause severe thrombocytopenia)

Question 10

What drugs are known to result in a primary hemostatic disorder causing thrombocytopenia?

Answer 10

• Chloramphenicol
• Estrogen

(Bone marrow toxicity resulting in thrombocytopenia / decreased PLT numbers)

Question 11

List causes of secondary IMTP

Answer 11

• Rickettsial diseases (RMSF, E.canis)
• Vaccines/ Medications given within the last 30 days
• Sytemic lupus erythematosus
• Neoplasias (Lymphoma, HSA, OSA)

(similar causes as IMHA)

Question 12

What is the drug treatment of choice for patients with IMTP?

Answer 12

• Prednisone (glucocorticoids) most frequently used
• Can use adjunct Vincristine, IVIG, Mycophenolate, Cyclophosphamide

Question 13

What should the PLT count be to consider a patient stable enough to be released from hospital?

Answer 13

PLT count > 15-20k (unlikely to need blood products or bleed out)

Question 14

When is a blood transfusion indicated for patients with thrombocytopenia?

Answer 14

• If concurrent anemia with PCV < 15%
• Transfuse with WHOLE BLOOD to maintain PCV while awaiting plt count increase

Question 15

How is vincristine used in the treatment of IMTP?

Answer 15

• Stimulates premature release of PLTs from bone marrow
• Decreases hospitalization time
• Not 1st line for IMTP!! Pred is

Question 16

What is IVIG therapy?

Answer 16

• Human immunoglobulins that temporarily block Fc receptors
• Used for IMTP to increase PLT count

NB: Human product so can cause severe anaphylaxis!!

Question 17

What is the prognosis of patients presenting with IMTP?

Answer 17

• Good prognosis if short term disease diagnosed within 1 month

Question 18

What diagnostic test findings are consistent with Von Willebrand disease?

Answer 18

• Increased BMBT
• PLT count usually normal
• PTT / ACT usually normal

Question 19

What are congenital causes of primary hemostatic disorders?

Answer 19

• vWD
• Basset hound thrombopathy

Question 20

Is PT or PTT prolonged first?

Answer 20

PT bc Factor 7 has the shortest half life

Question 21

What diagnostic test findings can be present in patients with Warfarin toxicity?

Answer 21

• Causes Vit K deficiency (Lack of factors 2,7,9,10)
• Normal PLTs (can be inc due to reactive thrombocytosis)
• Increased PT and aPTT
• Increased ACT
• Normal BMBT
• Regenerative anemia

Question 22

What CS do patients with Warfarin toxicity present with?

Answer 22

• Massive bleeding / hemorrhage
• Anemia, weak, palor
• Hypovolemia, shock
• Dyspnea if bleeding into thoracic cavity
• Lameness if bleeding into joint cavities
• Neuro signs if brain bleed

(Secondary hemostatic disorder / lack of clotting factors)

Question 23

What is the most common cause of SEVERE thrombocytopenia in dogs?

Answer 23

• IMTP

Question 24

What is Evans syndrome?

Answer 24

IMHA and IMTP together

Question 25

What PLT range would be concerning for risk of bleeding?

Answer 25

< 30k - 50k

Question 26

You run a CBC on a 5 year old king Charles spaniel presenting for wellness check and see evidence of thrombocytopenia. What is the next best diagnostic test to perform?

Answer 26

- Do peripheral blood smear!! - Have to R/O inherited macrothrombocytosis in Cav - R/O PLT clumping!!

Question 27

What are common causes of thrombocytopenia due to consumption in cats?

Answer 27

- FIP - Rickettsial diseases - DIC

Question 28

True or False: Hemorrhage can result in severe thrombocytopenia

Answer 28

False .... Exception: acute SEVERE hemorrhage Otherwise hemorrhage / blood loss usually causes a mild thrombocytopenia

Question 29

What neoplasias can cause secondary IMTP?

Answer 29

- High grade lymphoma - HSA - OSA (can cause IMHA too)