Page 162 - Cote clinical veterinary advisor dogs and cats 4th

62 Anemia, Immune-Mediated Hemolytic

Advanced or Confirmatory Testing over 10-14 days. Continue long-term
• Serologic and/or polymerase chain reaction antiplatelet therapy with clopidogrel or
VetBooks.ir ○ Dogs: dirofilariasis, ehrlichiosis, babesiosis, medications when immunosuppression and
(PCR) tests for
low-dose aspirin. Taper antithrombotic
PCV are stable.
anaplasmosis, Lyme, leptospirosis
○ Cats: hemotropic mycoplasmosis (PCR)
Possible Complications
TREATMENT • Thromboembolism (PTE, portal vein or
splenic thrombosis)
Treatment Overview ○ Avoid jugular intravenous catheters.
Therapy consists of immune suppression, • Secondary infections due to immunosup-
supportive care (improving or maintaining pressive therapy
perfusion and normal tissue oxygenation), and • Adverse drug side effects
anticoagulant therapy. For secondary IMHA, ○ Glucocorticoids: polyuria/polydipsia,
the cause should be addressed. polyphagia, gastrointestinal ulceration,
weakness, panting
Acute General Treatment ○ Cyclosporine: vomiting, diarrhea,
• Transfusion therapy decreased appetite, gingival hyperplasia
○ Maintenance of tissue oxygenation is the ○ Azathioprine: myelosuppression, hepa-
most important supportive therapy for topathy, pancreatitis
severely anemic patients. ○ Mycophenolate: diarrhea, decreased
○ Need indicated by clinical signs (e.g., appetite
tachypnea, dyspnea, tachycardia, bounding ○ Leflunomide: decreased appetite
pulses, weakness, collapse) rather than ANEMIA, IMMUNE-MEDIATED HEMOLYTIC • Antithrombotic therapy: excessive or inad-
numeric value of PCV. Positive slide agglutination test (macroagglutination/ vertent hemorrhage
○ Transfusion products: packed RBCs or clumping of cells) from a dog with primary IMHA. • Transfusion reactions (p. 989)
whole blood The test is performed with a drop of anticoagulated
• Immunosuppressive therapy blood mixed with a drop of saline. Recommended Monitoring
○ Glucocorticoids (cornerstone of IMHA • During acute crisis, mentation and respira-
therapy): prednisone (2 mg/kg PO q tory effort should be assessed frequently. PCV
24h or divided q 12h; for large-breed • For secondary IMHA, treatment of the should be assessed q 8-12h initially, then q
2
dogs, 40 mg/m /day) or dexamethasone underlying cause is essential and can reduce 12-24h while hospitalized.
sodium phosphate (0.15-0.25 mg/kg IV the need for and duration of additional • The PCV stabilizes in most dogs 4-6 days
q 24h) therapy. after starting immunosuppressive therapy.
○ When glucocorticoids fail to maintain • After discharge, PCV should be monitored
remission or produce unacceptable side Chronic Treatment weekly for the first month.
effects, additional immunosuppressive • Continue immunosuppression with gluco- • PCV should be evaluated before any dose
therapy should be administered. corticoids until well-established disease reduction during taper and 1 week after the
○ Cyclosporine 5 mg/kg PO q 12h remission (often ≥ 6 months) change in drug dose to detect a relapse.
○ Human immunoglobulin 0.5-1.5 g/kg • If single agent glucocorticoids fail to maintain
IV infused over 6-12 hours, up to 3 remission or produce unacceptable side PROGNOSIS & OUTCOME
doses may increase risk of thromboem- effects, adjunctive immunosuppressive
bolism. medications may be required. • Overall mortality rate for primary canine
• Antithrombotic therapy ○ Cyclosporine 5 mg/kg PO q 12h; phar- IMHA is estimated to be 20%-70%.
○ Anticoagulant therapy: low-molecular- macodynamic (or pharmacokinetic) • Negative prognostic indicators include
weight heparin (dalteparin 150 IU/kg SQ monitoring is recommended. nonregenerative anemia, thromboembolism,
q 8-12h or enoxaparin 0.8-1 mg/kg SQ ○ Azathioprine 2 mg/kg PO q 24h initial persistent autoagglutination, thrombocyto-
q 6-8h) or unfractionated heparin dose (dogs only) penia, leukocytosis with a left shift, and
(150-300 IU/kg SQ q 6-8h or CRI ○ Mycophenolate mofetil 10 mg/kg PO q hyperbilirubinemia.
10-25 IU/kg/h). The use of unfractionated 12h • Approximately 20% of dogs experienced a
heparin requires titration to prolong the ○ Leflunomide 2-4 mg/kg PO q 24h (dogs) clinical relapse within 1 year after cessation
activated partial thromboplastin time ○ Adjunctive immunosuppressive therapies of therapy, perhaps related to inadequate
(aPTT) to 1.5-3 × baseline values or can be used as acute therapy, but the onset treatment duration.
monitor anti-factor Xa activity. of action may be delayed by weeks • Thromboembolism is a major complication,
○ Antiplatelet therapy: clopidogrel (1-2 mg/ (azathioprine, mycophenolate mofetil, and and dogs receiving antithrombotic therapy
kg PO q 24h), or (less preferred) low-dose leflunomide). have improved outcomes.
aspirin (1-2 mg/kg PO q 24h [dogs]) if ○ Cyclophosphamide is not recommended. • Cats with primary IMHA have a lower overall
platelet count > 50,000/microL. • After the PCV stabilizes, taper the medication mortality rate, possibly due to a lower
• Additional supportive care dosage by 15%-25% every 2-4 weeks for incidence of thromboembolism.
○ Intravenous crystalloid fluids to support 4-8 months. Glucocorticoid tapering can
renal blood flow, especially in cases with occur more quickly if an adjunctive immu- PEARLS & CONSIDERATIONS
intravascular hemolysis nosuppressive agent is used. After glucocor-
○ Oxygen supplementation provides little ticoid dose is < 1 mg/kg/day, consider switch Comments
benefit for most anemic patients but to every other day dosing before additional • Spherocytes may develop after transfusion;
might be beneficial for patients with taper. a diagnostic blood smear should be evaluated
PTEs. • Thromboprophylaxis: Continue short-term before transfusion.
○ Gastric protectant: omeprazole (1 mg/kg anticoagulant therapy (low-molecular-weight • Dogs with IMHA die from anemia or
PO q 12h) heparin or unfractionated heparin) tapered thromboembolism.

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