Exotis ISSN 2398-2985

Reptiles

Anemia

Contributor(s): Vicky Strong, Yvette Rowntree

Introduction

  • Cause: increased loss (hemorrhage or hemolysis) or decreased production of red blood cells. In reptiles, most frequently a consequence of an underlying (often chronic) disease process.
  • Signs: weakness, exercise intolerance, reluctance to walk/move, tachycardia, dyspnea, pallor of the oral and cloacal mucosa.
  • Diagnosis: laboratory testing, fecal testing, radiography, ultrasonography, endoscopy, bone marrow aspiration/biopsy.
  • Treatment: directed at resolving the underlying cause.
  • Prognosis: variable, depending on the underlying cause/disease process.

Pathogenesis

Etiology

  • All causes of anemia fall into two major categories: increased loss of red blood cells or reduced red blood cell production.

Increased loss of red blood cells

  • Due to hemorrhage (most common):
    • Internal/external whole blood loss due to:
      • Trauma.
      • Surgery.
      • Coagulopathies.
      • Secondary rodenticide poisoning.
      • Heavy infestation with blood sucking parasites.
      • Gastrointestinal ulceration.
      • Neoplasia.
  • Due to hemolysis (less common):
    • Heavy metal toxicity, eg lead, zinc.
    • Idiosyncratic drug reaction.
    • Iatrogenic, eg due to excessive pressure applied during venipuncture, use of Calcium EDTA anticoagulant, prolonged sample storage, etc.
    • Immune mediated anemia (possible in theory, although not reported in reptiles).

Reduced red blood cell production

  • Usually secondary, due to anemia of chronic disease, eg:
    • Infectious disease.
    • Chronic inflammatory or degenerative renal, liver, lung or gastrointestinal disease.
    • General debilitation.
  • Can also be due to bone marrow disease (eg neoplasia, pure red cell aplasia), iron deficiency, toxicity, etc as in other species.

Pathophysiology

  • Regenerative anemia:
    • In an animal with normal functioning bone marrow, whole blood loss or RBC destruction results in the release of young/immature red blood cells into the bloodstream.
    • Due to the long half-life of a reptile RBC, this regenerative response can be delayed when compared with other, eg mammalian species. An absence of, eg polychromasia, for example, does not rule out a diagnosis of regenerative anemia. The hemogram must therefore be interpreted with care alongside the clinical history and physical examination findings.
  • In non-regenerative anemia there is no release of young/immature erythrocytes. This might be due to bone marrow disease, iron deficiency, toxicity, or more commonly due to chronic disease elsewhere in the body. The mechanisms by which this so called ‘anemia of chronic disease’ occurs include:
    • A shortening of RBC survival (caused by inflammatory cytokines).
    • Impaired erythropoiesis (RBC genesis) due to:
      • Reduced production of erythropoietin (EPO) and/or a blunting of the bone marrow’s response to EPO.
      • Alterations in iron metabolism.
  • Whatever the inciting cause (loss/reduced production of RBCs) anemia is characterized by a reduced amount of circulating hemoglobin in the body.
  • The consequence is therefore reduced oxygen delivery to the tissues.

Epidemiology

  • Often chronic, but patients may present in an acute-on-chronic.

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.
  • Saggese M D (2009) Clinical approach to the anemic reptile. J Exotic Pet Med 18 (2), 98-111 VetMedResource.
  • Sykes J M & Kaphlake E (2008) Reptile hematology. Vet Clin Exot Anim 11 (3), 481-500 VetMedResource.

Other sources of information

  • Braunstein E M (2018) Anemia of Chronic Disease. In: MSD Manual: Hematology and Oncology: Anemias Caused by Deficient Erythropoiesis. Merck & Co Inc, USA. Website: www.msdmanuals.com. Last accessed 30th January 2018.
  • Campbell T (2014) Clinical Pathology. In: Current Therapy in Reptile Medicine and Surgery. Eds: Mader D R & Divers S J. Saunders Elsevier, USA. pp 70-92. ISBN: 978-1-4557-0893-2.
  • Schumacker J (2008) Fluid Therapy in Reptiles. In: Zoo and Wild Animal Medicine Current Therapy. 6th edn. Eds: Fowler M E & Miller E. Elsevier Health Sciences, USA. pp 160-164.


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