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Differential Diagnosis: Anemia

Julie Allen, BVMS, MS, MRCVS, DACVIM (SAIM), DACVP (Clinical), Durham, North Carolina

Internal Medicine

|November/December 2020|Peer Reviewed

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Differential Diagnosis: Anemia

Following are differential diagnoses for patients presented with nonregenerative or regenerative anemia.

Nonregenerative Anemia*

  • Anemia of inflammatory/chronic disease
  • Chronic renal disease
  • Endocrine disease
    • Hyperestrogenism (eg, Sertoli cell tumor)
    • Hypoadrenocorticism
    • Hypothyroidism
  • Hemophagocytic syndrome (secondary to histiocytic sarcoma, lymphoma, or other neoplastic, infectious, or immune-mediated disease)
  • Hospital-acquired anemia (secondary to repeated blood sampling, surgery, inflammation, or hemodilution)
  • Iron deficiency anemia; can be regenerative initially (eg, secondary to GI bleeding, ectoparasites [eg, fleas], or lead toxicity)
  • Primary bone marrow disease (often with other concurrent cytopenias and/or dysplasia, except in cases of precursor-targeted immune-mediated anemia/pure red cell aplasia)
    • Congenital dyserythropoiesis
    • Drug-induced effect (often multifactorial [eg, estrogen, phenobarbital, sulfonamides])
    • Infectious disease (eg, FeLV/FIV, Ehrlichia spp, feline panleukopenia, canine parvovirus)
    • Myelodysplastic syndrome
    • Myelophthisis
      • Bone marrow necrosis/inflammation (eg, disseminated intravascular coagulation (DIC), sepsis, endotoxemia, drugs, toxins)
      • Myelofibrosis
      • Neoplasia (eg, lymphoma, leukemias, metastatic neoplasia)
    • Precursor-targeted immune-mediated anemia/pure red cell aplasia
  • Sideroblastic anemia

Regenerative Anemia

  • Hemolysis
    • Cold agglutinin disease 
    • Fragmentation anemia (eg, DIC, neoplasia [eg, hemangiosarcoma], liver disease, vasculitis, bacterial endocarditis, heartworm disease)
    • Hereditary cause
      • Feline congenital porphyria
      • Increased erythrocyte osmotic fragility (cats)
      • Phosphofructokinase deficiency (English springer spaniels, American cocker spaniels, whippets, Deutscher Wachtelhunds)
      • Pyruvate kinase deficiency (West Highland white terriers, Basenjis, beagles, cairn terriers, pugs, Labrador retrievers, domestic shorthair cats, Abyssinians, Somalis)
      • Spectrin deficiency (Dutch golden retrievers)
    • Hypophosphatemia (eg, treatment for diabetic ketoacidosis or refeeding syndrome)
    • Immune-mediated hemolytic anemia
      • Primary (idiopathic)
      • Secondary to underlying cause (eg, neoplasia, infection [eg, hemotropic Mycoplasma spp, Babesia spp], drugs, incompatible blood transfusion, envenomation)
    • Infectious cause (eg, hemotropic Mycoplasma spp, Babesia spp, Cytauxzoon felis, Leptospira spp)
    • Oxidant or Heinz body anemia (eg, secondary to onion or garlic ingestion, zinc toxicity [from pennies minted after 1982], copper toxicity [eg, copper hepatopathy], drugs [eg, acetaminophen, vitamin K], naphthalene, propylene glycol, benzocaine, skunk musk)
  • Hemorrhage
    • GI ulceration (eg, secondary to NSAID administration, neoplasia, hypoadrenocorticism)
    • Hemostatic disorders
      • Coagulation disorder (eg, rodenticide toxicity [vitamin K antagonists], inherited coagulation deficiency [eg, hemophilia A])
      • DIC
      • Thrombocytopathy (eg, secondary reaction to monoclonal gammopathy, drugs [eg, aspirin])
      • Thrombocytopenia (eg, immune-mediated thrombocytopenia)
      • Von Willebrand disease
    • Neoplasia (eg, splenic hemangiosarcoma)
    • Parasitic disease (eg, fleas, hookworms)
    • Trauma (eg, vehicular, bite wound)
    • Vessel wall disorder (eg, vasculitis, colonic vascular ectasia)
  • Normal puppies and kittens <8 weeks of age
Re-evaluation is needed after 4 to 5 days to ensure anemia is not preregenerative.


For global readers, a calculator to convert laboratory values, dosages, and other measurements to SI units can be found here.

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