THE CAUDAL VERTEBRAE FUSION AND DYSMORPHOLOGY IN WHITE SWISS SHEPHERD DOG – A CASE STUDY

The T-box gene belongs to a very large family of genes with the T motif. It encodes transcription factors that control the course of embryogenesis process. It plays a major role in the formation of the mesoderm – the layer from which the axial structures of the body develop. In dogs, its mutation causes a short tail in heterozygotes, often with a kink, while in recessive homozygotes it is lethal. Dominant homozygotes have phenotypically normal, long tails. The aim of this study was to identify carriers of the mutated allele of the T-box gene and to check whether it determines the occurrence of a lack of a tail and a kink in White Swiss Shepherds. Hair, blood, soft tissue and epithelium samples from the inner side of the cheek were collected from 23 individuals of the White Swiss Shepherd breed. Twenty-two individuals had phenotypically long tails and one was tailless. DNA was isolated, amplified using polymerase chain reaction (PCR), the product was subjected to electrophoretic separation in agarose gel, and then the obtained product was cut with the restriction enzyme Eco91I (BstEII) to be able to visualize the samples in a polyacrylamide gel. All dogs of the White Swiss Shepherd breed included in the study, whose DNA was analysed for carrying the 259C>G mutation of the T-box gene, turned out to be homozygous recessive with a long tail, which is consistent with the breed standard. The reason for the lack of a tail in one of the examined individuals must have been different mutation of the T-box gene or a mutation in another gene.