Glanzmann's Thrombasthenia (Great Pyrenees Type)

Other Names: Thrombasthenia, Thrombasthenic thrombopathia, GT
Affected Genes: ITGA2B
Inheritance: Autosomal Recessive
Mutation: chr9:19057144-19057157 (canFam3): 14 bp duplication (dup GGTGCCACAGACAT)
Breed(s): Great Pyrenees

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Common Symptoms

Glanzmann's thrombasthenia (great Pyrenees type) is an inherited bleeding disorder affecting dogs. Affected dogs have abnormal platelet activity. Platelets are blood cells that are necessary for the normal clotting of blood. Affected dogs usually present between 3 and 6 months of age with bleeding gums as their permanent teeth are erupting. Affected dogs often have recurrent nose bleeds until approximately 2 years of age. Affected dogs may also have skin bruising and increased and prolonged bleeding after surgery, after trauma and when in heat. The prognosis for affected dogs is good, but they are usually smaller than normal for their breed and must receive iron supplementation to prevent deficiency which can occur during growth or periods of chronic bleeding.

Testing Tips

Genetic testing of the ITGA2B gene will reliably determine whether a dog is a genetic Carrier of Glanzmann’s thrombasthenia (great Pyrenees type). Glanzmann’s thrombasthenia (great Pyrenees type) is inherited in an Autosomal Recessive manner in dogs meaning that they must receive two copies of the mutated gene (one from each parent) to develop the disease. In general, carrier dogs do not have features of the disease but when bred with another carrier of the same Mutation, there is a risk of having affected pups. Each pup that is born to this pairing has a 25% chance of inheriting the disease and a 50% chance of inheriting one copy and being a carrier of the ITGA2B gene mutation. Reliable genetic testing is important for determining breeding practices. In order to eliminate this mutation from breeding lines and to avoid the potential of producing affected pups, breeding of known carriers to each other is not recommended. Dogs that are not carriers of the mutation have no increased risk of having affected pups.

There may be other causes of this condition in dogs and a normal result does not exclude a different mutation in this gene or any other gene that may result in a similar genetic disease or trait.


  • Boudreaux MK, Kvam K, Dillon, AR, Bourne C, Scott M, Schwartz KA, Toivio-Kinnucuan M. Type I Glanzmann’s thrombasthenia in a Great Pyrenees dog. Vet Pathol. 1996 Sept; 33(5):503-511. [PubMed: 8885176]
  • Lipscomb DL, Bourne C, Boudreaux MK. Two genetic defects in alphaIIb are associated with type I Glanzmann's thrombasthenia in a Great Pyrenees dog: a 14-base insertion in exon 13 and a splicing defect of intron 13. Vet Pathol. 2000 Nov; 37(6):581-8. [PubMed: 11105947]