Tail length / brachyury / natural bobtail (TBXT-related) - Dog

What does this test examine?

This genetic test analyses the TBXT c.189C>G variant in dogs. The trait is also known as tail length, brachyury, T locus, natural bobtail, bobtail or congenital short tail.

What does this trait mean?

TBXT, also known as the T gene, has an important role in embryonic development of the tail and spine. One copy of the variant causes a naturally short or almost absent tail in many breeds. The visible tail length can vary, and other genetic factors may influence how short the tail becomes.

Inheritance and result

This trait is autosomal dominant. A dog with one copy of the variant usually shows natural bobtail. Two copies of the variant are embryonic lethal and are normally not expected in live puppies.

Practical value of this test

This test is useful for breeders and owners who want to confirm whether a short tail is explained by the tested TBXT variant. The result also helps avoid matings with an increased risk of embryonic loss from two bobtail alleles.

• Confirms whether natural short tail is caused by the tested TBXT variant.
• Helps distinguish genetic bobtail from other causes of tail length.
• Supports breeding decisions because two carriers together can produce a non-viable homozygous combination.
• Provides clear information for documentation, selection and communication about natural tail length.