This test enables you to identify if a dog will have a naturally long or short tail. This test can also identify if the dog's tail is naturally short or if it has been docked. This can be important while breeding two short tailed dogs together.
The condition known as "bob-tail" or "short tail" is caused by a mutation in the Brachyury gene (a gene that codes for an important protein). The inherited trait is autosomal dominant. This means that a dog only has to carry a single copy of the gene in order for the dog to have a bob-tail. Dogs that carry one (BT/bt) or two copies (BT/BT) of the mutation will have a natural short tail. Dogs with two copies of the normal gene (who are bt/bt) will have normal tail length.
In homozygous state (BT/BT), the Brachyury mutation is lethal in utero. For this reason, breeding two dogs with the bob-tail gene generally results in somewhat reduced litter sizes. This is important to realize when breeding short tailed dogs with one another.
Hytonen MK, Grall A, Hedan B, Dreano S, Seguin SJ, Delattre D, Thomas A, Galibert F, Paulin L, Lohi H, Sainio K, Andre C. Ancestral T-box mutation is present in many, but not all, short-tailed dog breeds. J Hered. 2009 Mar-Apr; 100(2):236-40. [PubMed: 18854372]
|BT/BT||Lethal: Dog has two copies of the bobtail gene mutation; this is thought to be lethal.|
|n/BT||Heterozygous: Dog carries one copy of the bobtail mutation and will have a natural bobtail. The dog may pass the gene on to any offspring.|
|n/n||Clear: Dog is negative for the bobtail gene mutation.|