Leukopenia
From Felipedia
Luekopenia (leucopaenia) is defined as a leukocyte count < 5500 cells/µl in cats.
Leukopenia is usually synonymous with neutropenia (< 2900 neutrophils/µl in dogs and < 2500 neutrophils/µl in cats) because neutrophils are the most numerous leukocyte in healthy blood. Neutropenia can develop alone or as a component of pancytopenia. Neutropenia is often accompanied by a left shift and toxic change (e.g., cytoplasmic basophilia, cytoplasmic vacuolation, Döhle's bodies, and toxic granulation)[1].
Neutropenia results from one of three mechanisms: 1) deficient neutrophil production in the bone marrow; 2) cells shifting from the circulating neutrophil pool to the marginal neutrophil pool in the blood; and 3) reduced neutrophil survival because of excessive tissue demand or immune-mediated destruction of cells. It is most commonly associated with infection because emigration of neutrophils from the blood into the tissues exceeds the rate at which the bone marrow can replace them.
Neutropenia predisposes the patient to systemic infection by a variety of pathogens. Many body systems can be affected in any combination depending upon the site(s) of infection.
Contents |
Causes
Deficient Neutrophil Production
Stem Cell Death or Inhibition
- Infectious agents - Feline Panleucopenia, FeLV and FIV and bacterial-induced myelonecrosis
- Drugs, chemicals, and toxins - chemotherapy agents, chloramphenicol and benzene-ring compounds, cephalosporins, griseofulvin and T-2 mycotoxin ingestion
Reduced Hematopoietic Space Secondary to Myelophthisis
- Bone marrow necrosis
- Myelofibrosis
- Osteopetrosis
- Disseminated neoplasia, leukemia, and myelodysplastic syndrome
- Disseminated granulomatous disease (histoplasmosis)
Cyclic Stem Cell Proliferation
- Inherited cyclic hematopoiesis (gray collie)
- FeLV infection
- Cyclophosphamide treatment
- Idiopathic disease
Neutrophil Migration
A shift in neutrophils from the circulating neutrophil pool (where they can be quantitated by the WBC count) to the marginal neutrophil pool (where they cannot be counted) occurs in patients with endotoxemia.
Reduced Survival Neutropenia
- Severe bacterial infection (most common cause) - pneumonia, peritonitis, and pyothorax
- Immune-mediated destruction
- Drug-induced destruction
- Hypersplenism (sequestration)
- Paraneoplastic syndrome (precise mechanism unknown)
References
1. August JR. Consultations in feline internal medicine. 2nd ed. Philadelphia: WB Saunders, 1994.
2. Duncan JR, Prasse KW, Mahaffey EA. Veterinary laboratory medicine. 3rd ed. Ames: Iowa State University Press, 1994.
3. Ettinger SJ, Feldman EC. Textbook of veterinary internal medicine. 4th ed. Philadelphia: WB Saunders, 1994.
4. Sherding RG. Cat diseases and clinical management. New York: Churchill Livingstone, 1989.
