Description:  Some dog breeds are characterized by extreme morphological differences from their ancestor, the wolf. One group of three breeds (Bulldog, French Bulldog and Boston Terrier) is characterized by a wide head, short muzzle, widely spaced eyes, small size and abnormalities of the vertebral bones of the back and tail. These breeds are referred to as the screw tail breeds since the characteristic that is unique and easy to see in these breeds is their shortened and kinked tails. These breed have become increasingly popular as pet dogs, although they have health issues associated with their morphology (Mansour et al. 2018).

The screw tail syndrome also known as Robinow-like syndrome is an inherited genetic disorder affecting the development of the tail vertebrae, resulting in a distinctive spinal curvature resembling a screw tail. This condition involves malformations and fusion of the vertebrae, leading to a kinked and shortened tail by approximately 8 to 15 vertebrae. In some breeds, the screw tail is a characteristic feature (Bulldog, French Bulldog and Boston Terrier). However, in other breeds, it is undesirable as it may be associated with health problems, including malformation of the thoracic vertebrae, brachycephalic airway obstruction syndrome, and congenital heart disease. The screw tail is caused by a mutation—a deletion of one cytosine nucleotide (c.2044delC)—in the WNT pathway gene Dishevelled 2 (DVL2). This mutation leads to a frameshift, premature inclusion of a stop codon, and the formation of a truncated, non-functional DVL2 protein that affects Wnt signaling.


Inheritance: autosomal recessive


Mutation: c.2044delC in the WNT pathway gene Dishevelled 2 (DVL2)


Sample: EDTA whole blood (1.0 ml) or 2 buccal brushes


The analysis is suitable for the following breeds: English Bulldog, American Bulldog, French Bulldog, American Pit Bull Terrier, American Staffordshire Terrier, Staffordshire Bull Terrier, Boston Terrier, Dogue de Bordeaux, and Shih Tzu


Notes: Although the Pug breed also has a curled tail, it is not classified as a screw tail because the tail is of normal length and free of vertebral malformations.