"Screw Tail" is a trait that causes a dog's tail to become shortened and kinked. It is most commonly associated with Bulldog breeds and Boston Terriers. Similar to Robinow Syndrome in humans, a frameshift mutation in the DVL2 gene leads to malformations in the vertebrae of the affected dog. The caudal vertebrae are most affected and are typically fused, leading to the distinctive kinked tail phenotype. However, is is possible that other vertebrae may also be affected.
It is important to note that not all breeds are affected by this mutation. There are several other reasons that a dog may have a shortened tail, which could be inherited or congenital.
|Affected: Dog has two copies of the screw tail mutation, and will have a shortened and kinked tail.
|Carrier: Dog carries one copy of the screwtail mutation, which may result in a partially kinked or shortened tail.
|Clear: Dog is negative for the mutation associated with a kinked or shortened tail.
Mansour TA, Lucot K, Konopelski SE, Dickinson PJ, Sturges BK, Vernau KL, Choi S, Stern JA, Thomasy SM, Döring S, Verstraete FJM, Johnson EG, York D, Rebhun RB, Ho HH, Brown CT, Bannasch DL. Whole genome variant association across 100 dogs identifies a frame shift mutation in DISHEVELLED 2 which contributes to Robinow-like syndrome in Bulldogs and related screw tail dog breeds. PLoS Genet. 2018 Dec 6;14(12):e1007850. [PubMed: 30521570]