L23: Clinical Approach To Petechia/Ecchymosis (Cooke) Flashcards
1ary hemostasis involves:
- Platelet abnormalities (reduced number or function)
- Vascular disorders
DIC involves both 1ary and 2ary hemostasis dysfx
:)
Rodenticide affects:
Clotting (coag factors) - 2ary hemostasis
-if they bleed enough, can also see low PLT counts
Von Willebrans breeds
Dobbies
Scotties
Which neoplasia can impact platelet numbers and sometimes function?
HSA
MM
LSA
Which infections commonly assoc. with vasculitis +/- 2ary immune mediated dz?
Rickettsial infection
Lepto
Secondary hemostasis involves:
Clotting factors
-usually involves bleeding into cavities
Great Pyrenese get what platelet disorder?
Glanzmann’s thrombasthenia (platelets lack fibrinogen receptor)
Shepherds get what platelet disorder
Hemophilia A (a coagulation defect that can lead to thrombocytopenia)
No proven link b/w vax and immune-mediated thrombocytopenia, however we are suspicious
:)
2ary hemostasis problem –> hemothorax –> muffled lung sounds
:)
Hematuria is less/more common in defects in primary hemostasis than defects of secondary hemostasis
Less
Hemarthrosis
Bleeding into joints
-usually a 2ary hemostatic defect
Most common cause of petechia/ecchymosis in the DOG**
Thrombocytopenia
3 mechs. Of thrombocytopenia
- decreased production
- increased consumption
- increased destruction
(Also sequestration less commonly)
Decreased production of platelets: differentials
- Drugs (chemo, TMS)
- Infection (viral, Rickettsial, fungal)
- Myelopthisis (effacement of BM w/ anything)
- Myelofibrosis (effacement of BM w/ fibrous tissue)
- Immune-mediated (attack of megakaryocytes)
- Neoplastic (can attack BM and result in immune-mediated dz)
Infectious causes of decreased platelet production
Viral: FeLV, FIV
Rickettsial: Ehrlichia, Anaplasma
Fungal: Histo
DIfferentials for Increased DESTRUCTION of PLT
- IMT (MOST COMMON)**
- Primary: Immune thrombocytopenia (ITP), Systemic Lupus Eryhthematosus (SLE)
-Secondary: Infection (ie. Lepto), Neoplasia (ie. Lymphoma), Drugs
SLE
Multisystem autoimmune dz char. By formation of Ab against wide array self-antigens and circulating immune complexes
Immune system becomes hyper-defensive
ITP
Immune-mediated thrombocytopenia
- autoimmune attack on own platelets
- initial cause unknown
- can be primary or secondary
Causes of Increased CONSUMPTION –> thrombocytopenia
- DIC (Most common cause)
- Vasculitis (Rickettsial dz/lepto)
- Neoplasia: HSA most common
- Inflammation
- Drug rxn
Misc. Ddx for petechia and ecchy
1) Thrombopathia (inherited or acquired)
2) Vascular disorders
- vasculitis due to rickettsial or IM dz (ie. RMSF)
- hyperadrenocorticism (causes inc. vascular fragility)
Inherited thrombopathias
- von Willebrand’s dz
- Glanzmann’s thrombasthenia
Acquired thrombopathias
- Drugs (aspirin, ace, NSAIDs)
- ace only dangerous if p already has clotting issues
- Systemic dz (uremia, liver dz)
- Hematologic disorders (Immune mediated thrombocytopenia, multiple myeloma)
Should look at blood smear to evaluate platelet count and rule out artifactual causes of low PLT count such as clumping. Also look for RBC morphology (ie. Spherocytes present?) and if other cell lines are affected
:)
If other cell lines besides platelets are NOT affected, what should you do next?
Rickettsial titers
FeLV/FIV
PT/PTT
+/- rads
If there is thrombocytopenia AND anemia (+/- neutropenia) and reticulocyte count is increased WITH hemolysis, what tests should you do next?
Slide agglutination test (to screen for IM dz ie. IMHA)
Coomb’s test (to detect Abs against RBCs)
Heartworm test (Can be explained by caudal caval syndrome)
+/- ANA (Antinuclear Ab test)
If there is thrombocytopenia AND anemia (+/- neutropenia) and reticulocyte count is increased WITHOUT hemolysis, what tests should you do next?
Total protein
- primary differential = blood loss
- not the same as Hct
If there is thrombocytopenia AND anemia (+/- neutropenia) and reticulocyte count is increased +/- LEUKOPENIA, what should you do next?
- Recheck (may be too soon and BM hasn’t responded yet)
- Bone marrow aspirate if persistently non-regenerative or have a pancytopenia
- FeLV/FIV
- go on tumor hunt if have pancytopenia
BMBT
- screening tool for primary hemostasis
- detects possible thrombopathia (platelet FUNCTION defect)
- not a very specific test
- predictive of surgical hemorrhage
- if prolonged, may indicate thrombocytopenia (40-50,000
- should submit vWF assay if prolonged
When is BMBT not needed?
If have SIGNIFICANT thrombocytopenia (
When should Chem be performed in P/E patient?
If looking for underlying sz (suspect DIC, systemic dz) or prior to initiation of therapy
Misc. diagnostics in P/E patient
- Abd. Rads: tumor hunt, splenomegaly
- Thoracic rads: mediastinal mass, HWD
- US if hepato/splenomegaly, to confirm abd. Mass
- Skin biopsy if suspect vasculitis
When do you suspect vasculitis?
-if have moderate thrombocytopenia, moderate anemia, pitting edema
PT/PTT evaluates:
SECONDARY hemostasis (clotting factors) -more specific than activated clotting time
Tx for presumptive IMT
Prednisone +/- :
Doxy Vincristine IVIG Azathioprine Cyclosporine Mycophenolate mofetil Leflunomide
