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56 Anemia, Aplastic

Anemia, Aplastic Client Education
Sheet
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○ Drug-associated: estrogen (dogs), cancer
BASIC INFORMATION
chemotherapeutic agents, sulfa drugs, marrow injury, and cell lines may recover
within 21 days.
Definition phenylbutazone, thiacetarsemide (dogs), ○ Chronic: marrow repopulation is
A bone marrow disorder that causes a bicy- griseofulvin (cats), methimazole (cats), uncertain, and recovery may require
topenia or pancytopenia in the blood and a albendazole, quinidine months.
hypocellular bone marrow with a majority of ○ Toxins: aflatoxin B 1 • Infectious disease serologic testing: Ehrlichia
the hematopoietic space replaced by adipose ○ Total-body irradiation canis, parvovirus as appropriate
tissue. Disorders with a pancytopenia and a ○ Starvation (cats)
normocellular or hypercellular bone marrow ○ Idiopathic
are not considered to be aplastic anemia. • Fever develops secondary to opportunistic TREATMENT
infection during neutropenia, and bleeding
Synonym develops during times of thrombocytopenia. Treatment Overview
Aplastic pancytopenia There is no specific treatment for aplastic
Epidemiology DIAGNOSIS anemia in dogs or cats, but supportive therapy
for neutropenia (broad-spectrum antibiotics)
SPECIES, AGE, SEX Diagnostic Overview and transfusions for anemia are essential until
Dogs and cats of any age and either sex Cytopenias are commonly observed on a CBC, the bone marrow recovers.
but a definitive diagnosis of aplastic anemia
RISK FACTORS requires histopathologic examination of the Acute General Treatment
• Cats: young, outdoor, male cats with roaming bone marrow. A thorough history should • Discontinue all medications or chemicals
and fighting behavior include exposure to drugs, toxins, chemicals, associated with the development of aplastic
○ Feline leukemia virus (FeLV)– and feline and infectious agents, especially 2-3 weeks anemia.
immunodeficiency virus (FIV)–positive before development of clinical signs. • Treat any identified underlying cause.
cats • Broad-spectrum antibiotics: for signs of
Differential Diagnosis infection or prophylactically if neutrophil
CONTAGION AND ZOONOSIS • Myelodysplasia (p. 671) count < 500-1000/mcL
• Retroviral infections, parvovirus • Neoplasia: myelophthisis, leukemia (pp. 586 • Transfusions (p. 1169)
and 588) ○ Anemia with clinical signs: whole blood
Associated Disorders • Myelofibrosis or packed red blood cells
• Fever associated with secondary infection; • Myelonecrosis ○ Thrombocytopenia and actively bleeding:
bleeding associated with thrombocytopenia fresh whole blood or platelet concentrate,
Initial Database generally reserved for life-threatening
Clinical Presentation • CBC: hemorrhage
DISEASE FORMS/SUBTYPES ○ Acute: granulocytopenia (neutropenia, ○ Donors should be universal or have the
• Acute: destruction of progenitor and prolif- eosinopenia) and thrombocytopenia occur same blood type as the recipient.
erative cells in the bone marrow within 2 first, and a nonregenerative anemia may ○ Cross-match before each transfusion
weeks of marrow injury. Neutropenia be absent or mild. because repeat transfusions are often
develops 5-6 days and thrombocytopenia ○ Chronic: moderate to marked granulocy- required
develops 8-10 days after marrow insult. Due topenia, thrombocytopenia, and non-
to the long erythrocyte life span, anemia is regenerative anemia Chronic Treatment
usually absent or mild. • Blood smear evaluation: • Bone marrow transplantation may be the
• Chronic: injury to all hematopoietic ○ No consistent abnormalities with aplastic superior treatment option but is not currently
stem cells creates a moderate to marked anemia, but a blood smear evaluation can feasible.
pancytopenia. identify other causes • Immunosuppressive therapy is commonly
• Serum biochemistry and urinalysis: used to treat aplastic anemia but may not
HISTORY, CHIEF COMPLAINT ○ Can help identify an underlying disorder be effective at enhancing the marrow
• Acute: neutropenia (lethargy, inappetence, or secondary complication (e.g., azotemia recovery.
fever), thrombocytopenia (hemorrhage) due to pyelonephritis) ○ Prednisolone 2 mg/kg PO q 24h (large-
2
• Chronic: same as acute plus signs of anemia • Cats: FeLV and FIV serologic testing breed dogs, 40 mg/m /day)
(weakness, tachypnea, collapse) ○ Cyclosporine 5 mg/kg PO q 12h (phar-
Advanced or Confirmatory Testing macodynamics monitoring recommended)
PHYSICAL EXAM FINDINGS • A definitive diagnosis of aplastic anemia ○ Azathioprine 2 mg/kg PO q 24h (dogs
• Acute: fever, petechia, hemorrhage requires a bone marrow biopsy (p. 1068). only)
• Chronic: same as acute plus pale mucous • A bone marrow aspirate allows identification ○ Mycophenolate mofetil 5-10 mg/kg PO
membranes, tachycardia, systolic heart of individual cells, but a core biopsy assesses q 12h
murmur marrow cellularity and architecture. • The therapeutic benefits of hematopoietic
○ Core biopsy: in aplastic anemia, hemato- growth factors, erythropoietin, and granu-
Etiology and Pathophysiology poietic cells constitute 0%-25% of the locyte colony-stimulating factor in dogs and
• Decreased or absent stem or progenitor cell marrow (50% in healthy marrow), with cats with aplastic anemia are unknown.
proliferation the remainder of the marrow space
• Potential causes: replaced with adipose tissue. Behavior/Exercise
○ Infectious: Ehrlichia spp, parvovirus, FeLV ○ Acute: stem cells repopulate the marrow Limit exposure of neutropenic dogs to other
and FIV within 10-14 days after the cessation of animals.

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