Spotlight on Hematology: Differential Diagnosis of Neutropenia

Following are differential diagnoses, listed in order of likelihood, for patients presented with neutropenia.

• Increased migration into tissue due to severe inflammation (eg, pneumonia, peritonitis) or acute endotoxemia due to increased margination; can occur within an hour of endotoxin release by gram-negative bacteria

• Decreased bone marrow production (often in association with other cytopenias) resulting from:

  • Chemotherapeutics

  • Estrogen toxicity (endogenous [eg, Sertoli cell tumor] vs exogenous)

  • Other drugs (eg, potentiated sulfonamides)

  • Myelophthisis

    • Myelofibrosis

    • Neoplasia (eg, lymphoblastic leukemia, multiple myeloma)

  • Bone marrow necrosis (eg, from sepsis, heatstroke, or drugs [eg, phenobarbital, carprofen, metronidazole, cyclophosphamide, colchicine, fenbendazole])

  • Canine parvovirus and feline panleukopenia virus

  • FeLV and FIV

  • Tick-borne disease (eg, Ehrlichia canis, E ewingii, Anaplasma phagocytophilum, babesiosis)

  • Gray collie syndrome (ie, cyclic hematopoiesis)

  • Trapped neutrophil syndrome of border collies

• Increased neutrophil destruction resulting from:

  • Immune-mediated neutropenia (primary or secondary [eg, to drugs or infection])

  • Hemophagocytic syndrome, often with other cytopenias

  • Histiocytic sarcoma, often with other cytopenias

  • Drugs

  • Toxins

  • Viruses

• Vitamin B12 deficiency, particularly in border collies, Australian shepherd dogs, giant schnauzers, and beagles

• Breed-associated cause of unknown mechanism, particularly in Belgian Tervurens and Australian shepherd dogs

• Idiopathic neutropenia (cats)

Editor’s note: This article was originally published in April 2019 as “Differential Diagnosis: Neutropenia.”