Hereditary osmotic fragility

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Hereditary erythrocyte osmotic fragility (hereditary spherocytosis) is a rare autosomal dominant genetic disease of dogs characterized by increased erythrocyte degradation and anemia[1].

This disease is caused by a genetic mutation in membrane structural proteins, the majority associated with missense mutations of spectrin molecules. In humans, distal renal tubular acidosis is an accompnaying condition but has not been reported in the dog[2].

The disease is characterized by blood smears showing anemia and erythrocytic spherocytosis and echinocytosis.

Hereditary erythrocytic osmotic fragility has been reported in the Miniature Schnauzer, Golden Retriever, Korean Jindo[3] and Alaskan Malamute[4].

Radioimmunoassays have revealed that erythrocyte spectrin concentration in affected dogs can be 50 - 65% of normal in dogs recovering from acute hemolytic anemia, where the osmotic fragility remains persistently increased[5].

Erythrocyte osmotic fragility can also occur secondary to other canine diseases that result in hemolytic anemia such as Babesia canis infections[6], immune-mediated hemolytic anemia, splenic torsion, pyruvate kinase deficiency and phosphofructokinase deficiency.

Most dogs are unaffected by this condition but its importance should be considered when establishing a differential cause of anemia.


  1. Giger U (2005) Regenerative anemias caused by blood loss or hemolysis, in Ettinger SJ, Feldman EC (eds): Textbook of Veterinary Internal Medicine, ed 6. St Louis, Saunders. pp:1886-1907
  2. Chang YH et al (2009) Compound mutations in human anion exchanger 1 are associated with complete distal renal tubular acidosis and hereditary spherocytosis. Kidney Int 76(7):774-783
  3. Yamato O et al (1999) Relation between erythrocyte reduced glutathione and glutamate concentrations in Korean Jindo dogs with erythrocytes possessing hereditary high activity of Na-K-ATPase and a high concentration of potassium. J Vet Med Sci 61(10):1179-1182
  4. Scott-Moncrieff JC et al (2001) Hemostatic abnormalities in dogs with primary immune-mediated hemolytic anemia. JAAHA 37(3):220-227
  5. Slappendel RJ et al (2005) J Vet Med Sci 61(10):1179-1182
  6. Paltrinieri S et al (2000) Haematological parameters and altered erythrocyte metabolism in anaemic dogs. J Comp Pathol 122(1):25-34