The ST Locus (Screw Tail) test reliably determines if a dog has one of the following genotypes at the ST locus:
This dog does not carry a copy of ST and has a genotype of N/N which does not result in a screw or kinked tail in the bully breeds. This dog will pass one copy of N to 100% of its offspring.
Interpretation: No kinked or screw tail
This dog carries one copy of ST which may result in a kinked tail. However, the degree to which a dog’s tail is affected cannot be determined. This dog will pass one copy of ST to 50% of its offspring and one copy of N to 50% of its offspring.
Interpretation: May have limited kinked tail
This dog carries two copies of ST which results in a kinked or screw tail in bully breed dogs. Although the DVL2 Mutation consistently affects the presentation of the tail, dogs with this mutation may have other vertebral abnormalities. This dog will pass one copy of ST to 100% of its offspring.
Interpretation: Kinked or screw tail