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Anemia: chronic disease
Introduction
- Cause: anemia may be due to decreased red cell production and/or increased red cell destruction.
- Low grade anemia due to reduced red cell production is common in the horse.
- Chronic inflammation is an important cause of anemia.
- In general this anemia is not severe and will resolve when the underlying cause is identified and treated.
- However, it may become profound and may then be slow to recover even after the initial cause is removed.
- Signs: most commonly related to the underlying disease process, but may include lethargy and poor performance.
- Diagnosis: identification of mild to moderate anemia on hematological evaluation.
- Treatment: treatment of the underlying disease should result in resolution of the anemia.
- Prognosis: good.
Presenting signs
Associated with- Chronic microbial infection.
- Chronic immunologic disorders.
- Neoplasia.
- Chronic liver disease.
- Chronic renal failure.
- Mineral deficiency: chronic disease anemia is manifest by iron deficiency in the presence of abundant body iron; iron deficiency is rarely a cause of anemia.
Pathogenesis
Etiology
- Mediators from abnormal cells selectively bind iron.
- Defects in erythropoietin production may further reduce red cell production.
- Antibodies generated to RBC altered by drug or neoplastic proteins lead to increased RBC destruction.
Predisposing factors
General- Chronic disease, inflammatory, immunologic or neoplastic.
- Auto-immune hemolytic anemia Anemia: auto-immune hemolytic (AIHA) , secondary to drug reaction or neoplasia.
- Red Maple toxicity.
- Folate deficiency, secondary to prolonged trimethroprim sulfonamide Trimethoprim medication (over 30 days).
Pathophysiology
- There are several mechanisms implicated in the development of anemia associated with chronic disease. Anemia occurs when the rate of production fails to meet the rate of destruction:
- A block in Fe release from storage.
- Defective bone marrow response to circulating erythropoietin.
- Decreased RBC life span.
- In terms of chronic microbial infection, anemia is protective. Low iron availability reduces bacterial growth rates.
- Lowered serum iron Blood: biochemistry - iron and reduced iron-binding capacity, with increased iron stored in mononuclear phagocytes.
- There appears to be some defect in the transfer of iron to erythrocyte precusor cells, Interleukin-1 has been implicated.
- Red cells become small and hypochromic (pale in color).
Timecourse
- Usually chronic - over weeks or months.
Diagnosis
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Treatment
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Prevention
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Borges A S, Divers T J et al (2007) Serum iron and plasma fibrinogen concentrations as indicators of systemic inflammatory diseases in horses. J Vet Intern Med 21 (3), 489-494 PubMed.
- Platt H (1987) Alimentary lymphomas in the horse. J Comp Pathol 97(1), 1-10 PubMed.
- Tennant B et al (1982) Six cases of squamous cell carcinoma of the stomach of the horse. Equine Vet J 14 (3), 238-243 PubMed.
- Franken P et al (1982) The bone marrow of the horse. II. Warm-blooded horses with anemia. Zentralbl Veterinarmed (A) 29 (1), 23-27 PubMed.