Test Detail

Molecular test for Glanzmann thrombasthenia (GT) in the Pyrenean Mountain Dog, an inherited disorder of platelet function due to a defect in the fibrinogen receptor GPIIb/IIIa that produces a haemorrhagic phenotype. It affects the haematological/haemostatic system and compromises surgery and wound management. The test reports clear/carrier/affected status for the corresponding variant.

Pyrenean Mountain Dog (Great Pyrenees). No consolidated carrier frequencies are published; the case series is limited to clinical cases and the molecular characterisation of the breed.

- Mucocutaneous bleeding tendency: epistaxis, gingivorrhagia\n- Spontaneous petechiae and ecchymoses or after minimal trauma\n- Prolonged post-surgical or post-traumatic bleeding\n- Normal platelet count with prolonged bleeding time\n- Absence of primary coagulopathy (PT/aPTT normal)

Glanzmann thrombasthenia was described in humans by Eduard Glanzmann in the early 20th century. In the dog, Boudreaux et al. (1996) described the type I form in the Pyrenean Mountain Dog (Great Pyrenees) and Lipscomb et al. (2000) identified in ITGA2B two molecular defects: a 14-bp duplication in exon 13 (c.1360_1373dup) and a splicing defect of intron 13, which alter the calcium-binding domain of the alphaIIb subunit (GPIIb). Boudreaux & Lipscomb (2001) reviewed the clinical, biochemical and molecular aspects of the disease in humans and dogs.

- Genotype breeding animals before mating\n- Do not mate carrier x carrier (25 % risk of affected homozygotes); carrier x clear produces 0 % affected and 50 % carriers\n- An affected animal must not be bred; a carrier can be mated to a clear animal without producing affected offspring\n- After a confirmed clinical case, do not repeat the parental mating and communicate the status to the buyer

Confirmation by blood count (normal platelet count), prolonged bleeding time and platelet aggregometry (absence of aggregation with ADP/collagen). Differentiate from von Willebrand disease (vWD, by vWF antigen assay) and from immune thrombocytopenias. Management: avoid NSAIDs and anticoagulants; platelet or plasma transfusion in active bleeding; haematological assessment before surgery.

1. Boudreaux MK et al. (1996) Type I Glanzmann's thrombasthenia in a Great Pyrenees dog. Vet Pathol 33(5):503-511. PMID: 8885176
2. Lipscomb DL et al. (2000) 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 37(6):581-588. PMID: 11105947
3. Boudreaux MK, Lipscomb DL (2001) Clinical, biochemical, and molecular aspects of Glanzmann's thrombasthenia in humans and dogs. Vet Pathol 38(3):249-260. PMID: 11355654
4. OMIA:001000-9615. Thrombasthenia in Canis lupus familiaris. https://omia.org/OMIA001000/9615/