IMTP Flashcards
What occurs during primary hemostasis?
Formation of a platelet plug via PLT adhesion (vWF), activation, and aggregation
What occurs during secondary hemostasis?
Coagulation factors are activated to produce end product of Fibrin that stabilizes the platelet plug formed during primary hemostasis
What coagulation factors are measured using PT?
Factor 7 (extrinsic pathway)
What coagulation factors are measured using aPTT?
12, 11, 9, 8 (intrinsic pathway)
What clinical signs can be seen if there is an issue with primary hemostasis?
- Petechia
- Ecchymosis
- Oozing blood from mucosal sites (mouth, eyes, GI tract, nose, bladder)
What clinical signs can be seen if there is an issue with secondary hemostasis?
- Bleeding into a body cavity
- Large SQ hematomas
- Larger scale blood loss that isn’t normally seen with primary hemostatic disorders
What diagnostics are used to assess primary hemostasis?
- 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)
What does an increased BMBT indicate?
- Primary hemostatic disorder
- Either a problem with PLT function or PLT numbers
- Consistent with marked thrombocytopenia
List the most common differentials for thrombocytopenia
- 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)
What drugs are known to result in a primary hemostatic disorder causing thrombocytopenia?
- Chloramphenicol
- Estrogen
(Bone marrow toxicity resulting in thrombocytopenia / decreased PLT numbers)
List causes of secondary IMTP
- Rickettsial diseases (RMSF, E.canis)
- Vaccines/ Medications given within the last 30 days
- Sytemic lupus erythematosus
- Neoplasias (Lymphoma, HSA, OSA)
(similar causes as IMHA)
What is the drug treatment of choice for patients with IMTP?
- Prednisone (glucocorticoids) most frequently used
- Can use adjunct Vincristine, IVIG, Mycophenolate, Cyclophosphamide
What should the PLT count be to consider a patient stable enough to be released from hospital?
PLT count > 15-20k (unlikely to need blood products or bleed out)
When is a blood transfusion indicated for patients with thrombocytopenia?
- If concurrent anemia with PCV < 15%
- Transfuse with WHOLE BLOOD to maintain PCV while awaiting plt count increase
How is vincristine used in the treatment of IMTP?
- Stimulates premature release of PLTs from bone marrow
- Decreases hospitalization time
- Not 1st line for IMTP!! Pred is
What is IVIG therapy?
- Human immunoglobulins that temporarily block Fc receptors
- Used for IMTP to increase PLT count
NB: Human product so can cause severe anaphylaxis!!
What is the prognosis of patients presenting with IMTP?
- Good prognosis if short term disease diagnosed within 1 month
What diagnostic test findings are consistent with Von Willebrand disease?
- Increased BMBT
- PLT count usually normal
- PTT / ACT usually normal
What are congenital causes of primary hemostatic disorders?
- vWD
- Basset hound thrombopathy
Is PT or PTT prolonged first?
PT bc Factor 7 has the shortest half life
What diagnostic test findings can be present in patients with Warfarin toxicity?
- 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
What CS do patients with Warfarin toxicity present with?
- 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)
What is the most common cause of SEVERE thrombocytopenia in dogs?
- IMTP
What is Evans syndrome?
IMHA and IMTP together
