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Diseases

Hematologic Diseases

Diagnosis and Treatment of Common Hematologic Diseases

Immune-Mediated Hemolytic Anemia (IMHA)

Cause:

Primary - Any breed (Cocker Spaniel, Bichon, Poodle, Old English Sheepdog, Collie)

Secondary

Infectious - Anaplasma, Babesia, Mycoplasma, Heartworm

Drugs - sulfas, beta lactams, certain toxins

Other - neoplasia, inflammation (eg. pancreatitis), envenomation

Direct Hemolytic Anemia - zinc (some pennies, toys, diaper cream, dog tags), hypophosphatemia, onion and garlic, acetaminophen

Signalment and Clinical Signs:

Average age 2-7y, female > male

Clinical Signs

Physical Exam

Lethargy/Weakness Anorexia Collapse Vomiting/Diarrhea Dark urine (bilirubin/hemoglobinuria)

Pallor

Tachycardia/tachypnea

Enlarged spleen and liver (25-50%)

Icterus

Pigmenturia

Hemic murmur (with marked anemia, resolves)

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Diagnosis:

Minimum Database:

CBC: mod-marked regenerative anemia (<0.25-0.30L/L) +/- spherocytosis (80-90%)

Extravascular hemolysis (more common, less severe) → icteric serum/urine

Intravascular serum → hemolytic serum/urine

Biochemistry: ↑ ALT (mild), ↑ bilirubin (moderate)

Urinalysis: bilirubinuria/hemoglobinuria

Specific Tests:

Slide Agglutination Test - 1 drop EDTA blood + 1 to 4 drops NaCl

Coomb’s Test (90%)

Rule out secondary causes:

Infectious - 4dx, serology

Neoplasia - abdominal ultrasound, thoracic rads

Treatment:

Goals:

Stabilize - blood transfusion, IV fluids

Immunosuppression

Prevent complications (ie. thromboembolism/DIC) - up to 80% of IMHA patients

Immunosuppression:

Corticosteroids (#1)

Prednisone (2mg/kg PO q24h) or Dexamethasone (0.25mg/kg IV q24h)

Omeprazole (Oakpark)

+/- Adjunct Immunosuppressive

Cyclosporine (5mg/kg BID or 10mg/kg SID)

ADR: GI, alopecia, gingival hyperplasia, immunosuppression

Azathioprine (2mg/kg PO q24h)

ADR: GI, pancreatitis, liver toxicity, BM suppression (do not use in cat)

Mycophenolate

ADR: diarrhea but NO myelosuppression or hepatotoxicity

Luflenomide

Antithrombotics (EXCEPT if severe thrombocytopenia <30,000/uL):

Clopidogrel (2mg/kg PO q24h)

Low-dose aspirin

Heparin

Rivaroxaban

Monitoring:

Repeat CBC

Initially every 12-24 hours until stable to discharge/manage as outpatient

Weekly until anemia resolved then wean

Wean 1 immunosuppressive at a time

Decrease by 25-50% every 2-4 weeks if CBC stable

If Hct declined since previous recheck, return to previous dose + taper slower

Prognosis:

Relapse rate 30%

Guarded-poor prognosis for longterm survival

Most deaths/euthanasia within first 2 months due to ongoing disease, complications

Feline IMHA

Cause: most young + secondary (Mycoplasma haemofelis, Feline leukemia virus)

Diagnosis: lower Hct (average 0.12L/L), can be non-regenerative, spherocytes NOT detectable, most extravascular, most Coomb’s positive

Treatment:

Immunosuppression: Corticosteroid +/- Adjunct (Cyclosporine most common)

Treat underlying disease (eg. Doxycycline for M. haemofelis)

No antithrombotics (thromboembolic complications rare in cats)

Can take months to respond, may be transfusion-dependent for some time

Immune-Mediated Thrombocytopenia (IMT/ITP)

Cause:

Primary or Secondary (like IMHA)

Other ddx: BM disease/neoplasia, infection (Ehrlichia, Anaplasma), DIC, platelet clumping

Signalment and Clinical Signs:

Average age 2-7y, female > male

Clinical Signs/Physical Exam

Pallor

Epistaxis

Petechiation/Ecchymoses

Melena

May be BAR with vital parameters

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Diagnosis:

Minimum Database:

CBC: marked thrombocytopenia (<50,000/uL) + mod-marked normocytic normochromic anemia + NO spherocytosis

Biochemistry:

Urinalysis:

Specific Tests:

Blood Smear - <2 platelets per HPF (normal: >15-20/HPF)

Rule out secondary causes:

Infectious - 4dx, serology

Neoplasia - abdominal ultrasound, thoracic rads

Treatment:

Goals:

Stabilize - blood transfusion, IV fluids

Immunosuppression

Prevent complications (ie. GI hemorrhage) - Omeprazole + restrict activity

Immunosuppression:

Corticosteroids (#1) - >70% improve to 50-100,000/uL in 1 week

Prednisone (2mg/kg PO q24h) or Dexamethasone (0.25mg/kg IV q24h)

+/- Adjunct Immunosuppressive

Vincristine (single dose)

ADR: GI, myelosuppression/neutropenia, soft tissue necrosis (IV)

Prognosis:

Low mortality 10-15% Relapse rate 30%

Recurrence 9-40%

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