Glanzmann Thrombasthenia in Great Pyrenees: Causes & DNA Testing

Glanzmann thrombasthenia is a hereditary blood clotting disorder that primarily affects the Great Pyrenees dog, also known in the USA as the Pyrenean Mountain Dog, along with some other related breeds. This disorder causes abnormal platelet function, which prevents the dog from forming proper blood clots, resulting in prolonged bleeding even from minor injuries.

The condition is autosomal recessive, meaning a dog must inherit two copies of the mutated gene to show symptoms. Dogs carrying only one copy of the gene do not display symptoms but can still pass the mutation to their offspring.

In this article, you will learn about Glanzmann thrombasthenia, how it affects dogs, breeds at risk in the US dog population, the genetics behind it, and the DNA testing options available in the USA that help breeders reduce the occurrence of this disease.

What is Glanzmann Thrombasthenia?

Glanzmann thrombasthenia (GT) is a genetic platelet disorder caused by a deficiency or defect in glycoprotein IIb/IIIa, a protein complex crucial for platelet aggregation and blood clotting. Dogs with GT have platelets that cannot properly stick together, leading to unstable clots. Even small cuts can cause significant, prolonged bleeding and delayed wound healing.

Signs often appear early in life, usually before a puppy turns one year old, including bleeding gums, spontaneous nosebleeds, unexplained bruises, blood in the urine or stool, and wounds that heal slowly. Some affected dogs may also be slightly smaller than typical for the breed.

Breeds Affected by Glanzmann Thrombasthenia in the USA

GT is mainly recognized in the Great Pyrenees breed, which faces considerable risk due to this mutation present in the breeding population in the US. Other breeds affected include the Otterhound and, to a lesser degree, the Basset Hound and Finnish Spitz, which have related bleeding disorders documented in veterinary medicine.

If you are looking to find a Great Pyrenees puppy, confirm that the breeder participates in genetic health screening, including testing for Glanzmann thrombasthenia.

How is Glanzmann Thrombasthenia Inherited?

The condition follows an autosomal recessive inheritance pattern, which means:

• Both parents must carry one copy of the mutated gene to possibly have affected puppies.
• If both parents are affected, all their puppies are affected.
• Carrier parents can have affected, carrier, or clear puppies depending on genetic combinations.
• A clear parent bred with an affected parent results in all carrier offspring.
• A clear parent bred with a carrier parent can produce both clear and carrier puppies.
• A carrier parent bred with an affected parent results in both carriers and affected puppies.

Therefore, knowing both parents’ genetic status is critical for breeders to prevent producing affected puppies.

DNA Testing for Glanzmann Thrombasthenia in the USA

In the United States, DNA testing for Glanzmann thrombasthenia is commercially available and widely used among reputable Great Pyrenees breeders. This test typically involves a blood sample or cheek swab collected by a licensed veterinarian and sent to a specialized genetic testing laboratory. The analysis identifies dogs as clear (free of the mutation), carriers (one copy of the mutation), or affected (two copies)

DNA testing has been accessible in the US since the late 1990s, making it a vital tool breeders use to screen their breeding stock to avoid carrier-to-carrier matings that produce affected puppies. It is recommended that prospective purchasers ask breeders for proof of these test results before acquiring a Great Pyrenees puppy, ensuring the new pet’s health.

Managing and Cares for Dogs with Glanzmann Thrombasthenia

Although there is no cure for Glanzmann thrombasthenia, proper management can help affected dogs live safer lives. Important care considerations include:

• Avoiding situations where the dog might get injured to reduce bleeding risks.
• Monitoring for bleeding signs such as gum bleeding or nosebleeds.
• Seeking immediate veterinary attention if bleeding episodes occur, which may require blood transfusions or supportive care.

Owners should maintain regular appointments with their veterinarian and keep their environment safe to minimize injury risks.

Other Breeds and Related Disorders

Besides the Great Pyrenees and Otterhound, bleeding disorders related to GT have also been documented in the Basset Hound and Finnish Spitz in the US. However, genetic testing programs in the US focus mainly on Great Pyrenees and Otterhound breeds.

Genetic testing combined with responsible breeding is key to reducing the incidence of hereditary blood clotting disorders and improving breed health overall.

Summary

Glanzmann thrombasthenia is a serious inherited blood clotting disorder that affects the Great Pyrenees and a few other breeds. Thanks to DNA testing available in the US and breed health initiatives, breeders and owners can now make informed decisions to reduce disease risk in puppies.

If you have or are thinking about getting a Great Pyrenees, working closely with your veterinarian and breeder about GT testing is essential to safeguard your dog’s health and wellbeing for many years to come.