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Erythrocyte morphology of dog with stomatocytosis and macrocytosis. Numerous stomatocytes are present in the field; representative stomatocyte indicated by arrow[1]

Stomatocytosis is an autosomal-recessive genetic disease of dogs characterized by abnormal erythrocyte phospholipid composition, causing leakage of sodium and potassium ions with subsequent hemolytic anemia[2].

The hereditary defect results in the basal permeability of erythrocytic membranes, which is always increased, and the extent of the increase correlates with the cellular dysfunction[3]. Mild glutathione deficiency can accompany hereditary stomatocytosis in dogs and appears to be a reflection of increased catabolism of glutathione by erythrocytes[4].

Hereditary canine stomatocytosis has been described in purebred Alaskan Malamutes, Drentse Patrijshonds[5] and Miniature Schnauzers[6].

Stomatocytosis in Standard Schnauzers is usually asymptomatic and is accompanied by minimal if any anemia[7].

Chondrodysplasia appears to occur concurrently with this condition in Alaskan malamutes[8]. Hereditary stomatocytosis and the associated anemia in chondrodysplastic Alaskan Malamutes have been characterized by macrocytosis, decreased mean corpuscular hemoglobin concentration (MCHC), low to normal hemoglobin concentration, reticulocytosis, increased osmotic fragility and shortened red cell survival[9].

Stomatocytes appear as 'bowl-shaped' erythrocytes in wet mounts and have an elongated, slit-shaped area of central pallor when viewed on dried blood films.

In affected dogs, hematological analysis reveals macrocytosis, decreased MCHC, slightly increased red cell diameter width and reticulocytosis. Percentages of stomatocytes in blood films are usually icnrease significantly, varying from 0.6 to 18.9% of all erythrocytes.

Erythrocyte osmotic fragility and intracellular Na+, K+ and 2,3-Diphosphoglycerate are frequently increased as well.

In dogs, this condition is associated with nonspecific liver disease, chronic anemia and familial stomatocytosis-hypertrophic gastritis (Ménétrier syndrome)[10].


  1. Brown DE et al (1994) Erythrocyte indices and volume distribution in a dog with stomatocytosis. Vet Pathol 31(2):247-250
  2. Renooij W et al (1996) Gastric mucosal phospholipids in dogs with familial stomatocytosis-hypertrophic gastritis. Eur J Clin Invest 26(12):1156-1159
  3. Stewart GW (1993) The membrane defect in hereditary stomatocytosis. Baillieres Clin Haematol 6(2):371-399
  4. Smith JE et al (1983) Glutathione metabolism in canine hereditary stomatocytosis with mild erythrocyte glutathione deficiency. J Lab Clin Med 101(4):611-616
  5. Slappendel RJ et al (1991) Familial stomatocytosis--hypertrophic gastritis (FSHG), a newly recognised disease in the dog (Drentse patrijshond). Vet Q 13(1):30-40
  6. Bonfanti U et al (2004) Stomatocytosis in 7 related Standard Schnauzers. Vet Clin Pathol 33(4):234-239
  7. Shmukler BE et al (2012) Cation-leak stomatocytosis in standard schnauzers does not cosegregate with coding mutations in the RhAG, SLC4A1, or GLUT1 genes associated with human disease. Blood Cells Mol Dis 48(4):219-225
  8. Fletch SM et al (1975) The Alaskan malamute chondrodysplasia (dwarfism-anemia) syndrome - in review. J Am Anim Hosp Assoc 11:353-336
  9. Pinkerton PH et al (1974) Hereditary stomatocytosis with hemolytic anemia in the dog. Blood 44:557-567
  10. Slappendel RJ et al (1994) Normal cations and abnormal membrane lipids in the red blood cells of dogs with familial stomatocytosis-hypertrophic gastritis. Blood 84(3):904-909