Glanzmann Thrombasthenia in Pyrenean Mountain Dogs: Causes & Testing

Glanzmann thrombasthenia is an inherited blood clotting disorder affecting mainly the Pyrenean mountain dog, also known as the Great Pyrenees, and a few other breeds. It causes defective platelet function, which impairs the dog's ability to form blood clots leading to prolonged bleeding even from small injuries.

This condition is autosomal recessive, meaning a dog must inherit two copies of a mutated gene to be affected, while carriers with one copy show no symptoms but can pass the gene to their puppies.

In this guide, you will learn what Glanzmann thrombasthenia is, how it affects dogs, the breeds involved, inheritance patterns, and how DNA testing in the UK helps responsible breeders reduce the disease.

What is Glanzmann Thrombasthenia?

Glanzmann thrombasthenia (GT) is a genetic platelet disorder where the blood platelets lack functioning glycoprotein IIb/IIIa, a complex critical for platelet aggregation and blood clot formation. Dogs with GT have defective platelets unable to form stable clots, so even minor wounds can cause severe, prolonged bleeding and poor wound healing.

Clinical signs can appear early, often before the dog is a year old, and include bleeding gums, frequent nosebleeds, bruising, blood in the urine or faeces, and slow healing of injuries. Some affected dogs may be smaller than average for their breed.

Which Breeds Are Affected?

GT is primarily recognised in the Pyrenean mountain dog breed, placing them at significant risk due to the gene's presence in the breeding population. Other breeds affected include the Otterhound and, to a lesser extent, related conditions have been documented in Basset hounds and Finnish Spitz. This highlights the importance of breed-specific health screening.

If you are interested in finding a Pyrenean mountain dog puppy, ensure the breeder participates in health testing for this condition.

How is Glanzmann Thrombasthenia Inherited?

The inheritance of GT is autosomal recessive, which means:

• Both parents must carry one copy of the mutated gene to produce affected puppies.
• Affected parents will have affected litters.
• Carrier parents can produce affected, carrier, or clear puppies depending on genetic combinations.
• A clear parent bred with an affected parent will produce carrier puppies.
• A clear parent bred with a carrier parent will produce a mix of clear and carrier puppies.
• A carrier parent bred with an affected parent will produce both carrier and affected puppies.

Thus, knowing the genetic status of both breeding dogs is crucial for preventing affected babies.

DNA Testing for Glanzmann Thrombasthenia in the UK

Health screening through DNA testing is now widely accessible for the Pyrenean mountain dog in the UK. A simple blood or buccal swab sample taken by a vet is sent to an approved laboratory specialising in genetic tests to determine if a dog is clear, a carrier, or affected.

The Kennel Club’s DNA testing scheme supports breeders by officially recording results and advising on safe mate pairings.

If you are considering buying a Pyrenean mountain dog, always ask the breeder for proof of parental DNA test results to ensure you’re getting a healthy puppy and avoiding health complications later.

Managing and Caring for Affected Dogs

While there is no cure for Glanzmann thrombasthenia, careful management is key. Affected dogs require:

• Minimising risk of injury to prevent bleeding episodes.
• Close monitoring for signs of bleeding such as gum or nose bleeds.
• Immediate veterinary care if bleeding occurs, which may include transfusions or supportive treatments.

Owners of affected dogs should maintain regular veterinary check-ups and maintain a safe environment.

Other Breeds and Related Conditions

Besides the Pyrenean mountain dog and Otterhound, related bleeding disorders have been identified in breeds like the Basset hound and Finnish Spitz. However, the breeding control schemes and DNA testing focus primarily on the Pyrenean mountain dog and Otterhound breeds in the UK.

Responsible breeding combined with genetic testing is essential to reduce the frequency of these hereditary conditions and improve overall breed health.

Conclusion

Glanzmann thrombasthenia is a serious hereditary blood clotting disorder affecting the Pyrenean mountain dog and some other breeds. Thanks to advances in DNA testing and breed health initiatives in the UK, breeders and owners can now make informed decisions to reduce the risk of this condition in puppies.

If you own a Pyrenean mountain dog or are considering one, engaging with your vet and breeder about Glanzmann thrombasthenia testing is vital to ensure your dog’s health and wellbeing for years to come.