Anemia: immune-mediated hemolytic

Introduction

• Very rare in the cat.
• Signs : pallor, lethargy.
• Cause : antibody-mediated destruction of red cells by intravascular or extravascular hemolysis.
• May be secondary to infection with FeLV and/or  Haemoplasmas (feline infectious anemia).
• Primary AIHA is much less common in the cat than in the dog.
• Diagnosis : hematology, Coombs' test.
• Treatment : treat underlying disease +/- immunosuppressive therapy.
• Prognosis : guarded.

Diagnosis

Clinical signs

• Pallor.
• Pyrexia.
• Tachycardia and tachypnea.

• Jaundice (rare).
• Hepatosplenomegaly.

• Lymphadenopathy.

• Hemoglobinuria.

Diagnosis

Differential diagnosis

• Blood loss anemia    .
• Hemolytic anemia:
  • Heinz body anemia, (onion toxicity  [Allium species poisoning]  , exogenous oxidant drugs).
    Heinz bodies may be found in up to 10% of the red cells of normal cats.
  • Erythrocyte defects, (PK deficiency     of Abyssinian, Somali and occasional domestic short hairs).
  • Hypophosphatemia     in cats with diabetes mellitus    , or hepatic lipidosis    .
  • Infectious causes (haemoplasmas  [Mycoplasma haemofelis, 'Candidatus Mycoplasma haemominutum' and 'Candidatus Mycoplasma turicensis']  ).
  • Microangiopathic anemia.
  • Neonatal isoerythrolysis    .
  • Acute transfusion reactions    .
• Anemia of renal  [Kidney: chronic kidney disease]  , or hepatic disease.
• FeLV-induced red cell aplasia  [Feline leukemia virus disease]  .

• Stem cell damage by FeLV, FIE, Ehrlichia (rare in cats), drugs or chemicals resulting in pancytopenia.
• Anemia of chronic disease.
• Myelophthisis secondary to bone marrow inflammation or neoplasia (lymphoma    , lymphoid leukemia    , myeloproliferative disease).

Outcomes

Expected response to treatment

• Increasing PCV.

Reasons for treatment failure

• Failure to identify and treat underlying disease.