Aplastic pancytopenia (aplastic anemia) is a rare immune-mediated myelodysplastic syndrome of dogs characterized by anemia and adipose infiltration of bone marrow.
The disease is characterized by pancytopenia (reduced red and white cell numbers) in peripheral blood, associated with bone marrow hypocellularity.
Of cases reported in the literature, a number of etiological agents have been identified, including:
- Canine parvovirus
- Monocytic ehrlichiosis
- Sertoli cell tumor
- Polyostotic lymphoma
- Lupus erythematosus
- Drug reactions (e.g. stilboestrol, phenylbutazone, meclofenamic acid, cephalosporins, trimethoprim-sulfamethoxazole, albendazole, thiacetarsamide, captopril, griseofulvin, quinidine
- Exposure to radiation
Clinically affected dogs are often young, but in cases where an underlying etiology is established, dogs can be of any age. General symptoms are often vague, including lethargy, fever (if secondary bacterial infection is present), weight loss and occasional vomiting.
Diagnosis is usually one of exclusion. Serology for Ehrlichia canis, antinuclear antibodies and fecal ELISA for parvovirus antigen are strongly recommended.
Imaging by MRI and bone marrow histological examination are usually required for establisshing a definitive diagnosis. In young dogs, most of the marrow is active red marrow composed of precursors for red cells, white cells, and platelets. In adult dogs, there is a change to inactive yellow marrow that is predominantly composed of fat.
Treatment primarily aims at immunosuppressive therapy with high-dose prednisolone and azathioprine (2 mg/kg orally twice daily) or cyclosporine (5 mg/kg orally twice daily). Fortnightly blood transfusions may be required if PCV < 15.
The use of broad-spectrum antimicrobials is recommended if a secondary bacterial infection is suspected.
Although the prognosis is guarded, some dogs with aplastic pancytopenia recover.
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