Pancytopenia is the decrease in all circulating hematologic cell lines. It can result from either peripheral destruction of blood cells or a primary insult to the bone marrow. In dogs and cats, many infectious, immune-mediated, and neoplastic conditions have been associated with pancytopenia. In cases of decreased hematopoietic cell production, bone marrow aspirates and/or core marrow biopsy samples are usually required to accurately characterize the marrow disease. The prognosis in pancytopenic patients is variable and depends upon the underlying cause.

Decreased Hematopoietic Marrow Cell Production

Marrow Hypoplasia or Aplasia
Estrogen (endogenous and exogenous) and other drugs, infectious disease, idiopathic or immune-mediated disease.

Marrow Necrosis
Septicemia, neoplasia, drugs, immune-mediated disease, infectious disease.

Myelodysplasia
Primary or secondary from immune-mediated disease, neoplasia, infectious disease, drugs.

Marrow Fibrosis or Sclerosis
Marrow necrosis, neoplasia, pyruvate kinase deficiency, drugs, immune-mediated disease.

Myelophthisis
Neoplasia, granulomatous disease
(histoplasmosis, visceral leishmaniasis).

Increased Hematopoietic Cell Production

Sepsis

Immune-Mediated Disease

Hemophagocytic Syndrome or Hypersplenism
Primary or secondary from immune-mediated disease, myelodysplasia, neoplasia, infectious disease.

When assessing potential causes of pancytopenia, the patientŐs historical information should address: recent use of therapeutic drugs or preventatives, including potential for exposure to human prescription or over-the-counter medications; vaccination within the previous 30-45 days; travel outside of the immediate area or to another country; exposure to other animals of unknown health status; previous health issues; exposure to chemicals or radiation; and presence of two testicles currently or before neutering.

Categories of drugs associated with pancytopenia include: Non-steroidal anti-inflammatories (NSAIDs), chemotherapeutics, antibiotics, anthelmintics, and miscellaneous.

NSAIDS
Phenylbutazone, meclofenamic acid (Arquel), and potentially any NSAID in susceptible breeds, families or individuals.

Chemotherapeutics
Cyclophosphamide, cytosine arabiboside, doxyrubicin, vinblastine, hydroxyurea, cyclohexylchlorethylnitrosurea (CCNU), 5-fluorouracil, cyclosporine, carboplatin, and azathioprine.

Antibiotics
Potentiated sulfonamides and cephalosporins.

Anthelmintics
Albendazole and fenbendazole.

Miscellaneous
Quinidine, thiacetarsimide, captopril, griseofulvin, methimazole, and estrogen.