Macrothrombocytopenia / thrombocytopenia (TUBB1-related) - Cairn and Norfolk Terrier

What does this test analyse?

This genetic test analyses the TUBB1 c.5G>A variant for macrothrombocytopenia and thrombocytopenia in dogs. The condition is also known as MTC, inherited low platelet count and thrombocytopenia with enlarged platelets. TUBB1 encodes beta-1 tubulin, a structural protein that is important for platelet formation from megakaryocytes.

What does this condition mean?

In Cairn and Norfolk Terriers, the tested variant can lead to a reduced platelet count and relatively large platelets. On routine bloodwork this can resemble acquired thrombocytopenia, while in this context it can be inherited. Depending on genotype and breed context, dogs may show few clinical signs or may be more prone to bruising, petechiae, prolonged bleeding after trauma or additional attention around procedures.

Inheritance and result

This test interprets the trait as autosomal recessive. A clear dog does not carry the tested variant. A carrier has one copy and can pass it on. A dog with two copies has the genetic form of TUBB1-related macrothrombocytopenia/thrombocytopenia.

Practical value of this test

• Helps breeders identify carriers and affected genotypes before mating decisions are made.
• Supports breeding choices and prevents two carriers being paired unknowingly.
• Gives veterinarians and owners genetic context when platelet counts are low or platelets are unusually large.
• Helps distinguish inherited thrombocytopenia from other explanations when bloodwork is abnormal.

When is this especially useful?

The test is useful before breeding, before selecting relatives from a known risk line and when laboratory findings show low platelet counts. A DNA result makes the difference between free, carrier and affected genotype explicit, so breeding, clinical interpretation and owner communication can be based on clear genetic information.

Interpreting bloodwork

A genetic result is practical here because low platelet counts do not always mean the same thing. In a dog with the tested TUBB1 variant, an abnormal count can reflect an inherited platelet variant, especially when the platelets are also larger than normal. This helps results to be assessed more consistently, avoids unnecessary confusion and supports better planning for breeding, check-ups or procedures where bleeding risk matters.