L23: Clinical Approach To Petechia/Ecchymosis (Cooke)

Question 1

1ary hemostasis involves:

Answer 1

• Platelet abnormalities (reduced number or function)

- Vascular disorders

Question 2

DIC involves both 1ary and 2ary hemostasis dysfx

Answer 2

:)

Question 3

Rodenticide affects:

Answer 3

Clotting (coag factors) - 2ary hemostasis

-if they bleed enough, can also see low PLT counts

Question 4

Von Willebrans breeds

Answer 4

Dobbies

Scotties

Question 5

Which neoplasia can impact platelet numbers and sometimes function?

Answer 5

HSA
MM
LSA

Question 6

Which infections commonly assoc. with vasculitis +/- 2ary immune mediated dz?

Answer 6

Rickettsial infection

Lepto

Question 7

Secondary hemostasis involves:

Answer 7

Clotting factors

-usually involves bleeding into cavities

Question 8

Great Pyrenese get what platelet disorder?

Answer 8

Glanzmann’s thrombasthenia (platelets lack fibrinogen receptor)

Question 9

Shepherds get what platelet disorder

Answer 9

Hemophilia A (a coagulation defect that can lead to thrombocytopenia)

Question 10

No proven link b/w vax and immune-mediated thrombocytopenia, however we are suspicious

Answer 10

:)

Question 11

2ary hemostasis problem –> hemothorax –> muffled lung sounds

Answer 11

:)

Question 12

Hematuria is less/more common in defects in primary hemostasis than defects of secondary hemostasis

Answer 12

Less

Question 13

Hemarthrosis

Answer 13

Bleeding into joints

-usually a 2ary hemostatic defect

Question 14

Most common cause of petechia/ecchymosis in the DOG**

Answer 14

Thrombocytopenia

Question 15

3 mechs. Of thrombocytopenia

Answer 15

• decreased production
• increased consumption
• increased destruction

(Also sequestration less commonly)

Question 16

Decreased production of platelets: differentials

Answer 16

• 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)

Question 17

Infectious causes of decreased platelet production

Answer 17

Viral: FeLV, FIV
Rickettsial: Ehrlichia, Anaplasma
Fungal: Histo

Question 18

DIfferentials for Increased DESTRUCTION of PLT

Answer 18

• IMT (MOST COMMON)**
• Primary: Immune thrombocytopenia (ITP), Systemic Lupus Eryhthematosus (SLE)

-Secondary: Infection (ie. Lepto), Neoplasia (ie. Lymphoma), Drugs

Question 19

SLE

Answer 19

Multisystem autoimmune dz char. By formation of Ab against wide array self-antigens and circulating immune complexes

Immune system becomes hyper-defensive

Question 20

ITP

Answer 20

Immune-mediated thrombocytopenia

• autoimmune attack on own platelets
• initial cause unknown
• can be primary or secondary

Question 21

Causes of Increased CONSUMPTION –> thrombocytopenia

Answer 21

• DIC (Most common cause)
• Vasculitis (Rickettsial dz/lepto)
• Neoplasia: HSA most common
• Inflammation
• Drug rxn

Question 22

Misc. Ddx for petechia and ecchy

Answer 22

1) Thrombopathia (inherited or acquired)
2) Vascular disorders
- vasculitis due to rickettsial or IM dz (ie. RMSF)
- hyperadrenocorticism (causes inc. vascular fragility)

Question 23

Inherited thrombopathias

Answer 23

• von Willebrand’s dz

- Glanzmann’s thrombasthenia

Question 24

Acquired thrombopathias

Answer 24

• 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)

Question 25

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

Answer 25

:)

Question 26

If other cell lines besides platelets are NOT affected, what should you do next?

Answer 26

Rickettsial titers FeLV/FIV PT/PTT +/- rads

Question 27

If there is thrombocytopenia AND anemia (+/- neutropenia) and reticulocyte count is increased WITH hemolysis, what tests should you do next?

Answer 27

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)

Question 28

If there is thrombocytopenia AND anemia (+/- neutropenia) and reticulocyte count is increased WITHOUT hemolysis, what tests should you do next?

Answer 28

Total protein - primary differential = blood loss - not the same as Hct

Question 29

If there is thrombocytopenia AND anemia (+/- neutropenia) and reticulocyte count is increased +/- LEUKOPENIA, what should you do next?

Answer 29

- 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

Question 30

BMBT

Answer 30

- 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

Question 31

When is BMBT not needed?

Answer 31

If have SIGNIFICANT thrombocytopenia (

Question 32

When should Chem be performed in P/E patient?

Answer 32

If looking for underlying sz (suspect DIC, systemic dz) or prior to initiation of therapy

Question 33

Misc. diagnostics in P/E patient

Answer 33

- Abd. Rads: tumor hunt, splenomegaly - Thoracic rads: mediastinal mass, HWD - US if hepato/splenomegaly, to confirm abd. Mass - Skin biopsy if suspect vasculitis

Question 34

When do you suspect vasculitis?

Answer 34

-if have moderate thrombocytopenia, moderate anemia, pitting edema

Question 35

PT/PTT evaluates:

Answer 35

``` SECONDARY hemostasis (clotting factors) -more specific than activated clotting time ```

Question 36

Tx for presumptive IMT

Answer 36

Prednisone +/- : ``` Doxy Vincristine IVIG Azathioprine Cyclosporine Mycophenolate mofetil Leflunomide ```