Glanzmann Thrombasthenia Type I (Discovered in Great Pyrenees)

Glanzmann Thrombasthenia (GT) Type I is a blood disorder characterized by poor blood platelet aggregation. Platelet in the blood are needed to help start clot formation, so as a result of this disorder bleeding may be prolonged.

Key Signs

Nose bleeds, Bleeding from the gums, Prolonged bleeding during trauma or surgery

Age of Onset

At birth

Present at birth


Autosomal Recessive

For autosomal recessive disorders, dogs with two copies of the variant are at risk of developing the condition. Dogs with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their puppies if bred.

Likelihood of the Condition

High likelihood

At risk dogs are highly likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a dog with GT

Partner with your veterinarian to make a plan regarding your dog’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about GT

Glanzmann thrombasthenia causes susceptibility to bleeding due to poor blood platelet aggregation. This is caused by a deficiency in a platelet membrane glycoprotein. Typical clinical signs include mucosal bleeding, such as nose bleeding, bleeding from the gums, intestinal bleeding, as well as blood in the urine. Blood spots under the skin or in the mouth may be observed. More severe, prolonged bleeding may occur due to a trauma or surgery.

Affected dogs should be monitored closely for excessive and prolonged bleeding during and after any required surgical procedures or after any trauma. Supportive care during bleeding episodes is indicated. Blood or platelet transfusions should be provided as necessary to ensure proper clotting if other means are unsuccessful.

For Breeders

Planning to breed a dog with this genetic variant?

There are many responsibilities to consider when breeding dogs. Regardless of test results it is important that your dog is in good general health and that you are in a position to care for the puppies if new responsible owners are not found. For first time or novice breeders, advice can be found at most kennel club websites.

This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to occur. A carrier dog with one copy of the GT mutation can be safely bred with a clear dog with no copies of the GT mutation. About half of the puppies will have one copy (carriers) and half will have no copies of the GT mutation. A dog with two copies of the GT mutation can be safely bred with a clear dog. The resulting puppies will all be carriers. Puppies in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected puppies. Please note: It is possible that disease signs similar to the ones caused by the GT mutation could develop due to a different genetic or clinical cause.

Technical Details

Variant C>G
Chromosome 9
Coordinate Start 19,057,157
Coordinate End 19,057,158

All coordinates reference CanFam3.1

References & Credit

Credit to our scientific colleagues:

Lipscomb, D. L., Bourne, C., & Boudreaux, M. K. (2000). Two genetic defects in αIIb 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. Veterinary Pathology, 37(6), 581–588. View the article