Breeds: Pembroke Welsh Corgi, Australian Shepherd, Australian Stumpy Tail Cattle Dog, Bourbonnais Pointer, Brazilian Terrier, Brittany, Jack Russell Terrier, Mudi, Polish Lowland Sheepdogy, Berger des Pyrénées, Schipperke, Spanish Waterdog, and others
Samples Accepted: Blood, Buccal Swabs
Trait Information: Bobtail, also known as Brachyury, is a naturally occurring short tail.
Inheritance Information: Bobtail is autosomal dominant, meaning that animals with just one copy of this allele will show the phenotype, and 50% of their offspring will also show this trait. This trait is homozygous lethal, meaning that individuals with two copies of the allele do not survive to birth.
The possible genotypes are:
n/n The dog has a normal length tail.
B/n The dog has a short tail, and can pass the allele on to approximately 50% of any offspring. If bred to another B/n bobtail dog, approximately 25% of the offspring will have normal tails (n/n), 50% will be bobtail (B/n), and 25% will not be born. Therefore, when a litter is born, the expected ratio would be 33% normal tailed, 66% bobtail. If bred to a dog with a normal length tail (n/n), approximately 50% will be bobtail and 50% will be normal tailed.
– If breeding two bobtail dogs, expect to have slightly reduced litter sizes, because 25% of expected pups will not be born.
Test Information: This mutation test identifies a single base change in the T gene. Be aware that there are short tailed dogs for which the trait is not caused by this mutation.
Haworth, K., Putt, W., Cattanach, B., Breen, M., Binns, M., Lingaas, P., Edwards, Y.H.: Canine homolog of the T-box transcription factor T; failure of the protein to bind to its DNA target leads to a short-tail phenotype Mammalian Genome 12:212-218, 2001. Pubmed reference: 11252170. DOI: 10.1007/s003350010253
Hytönen, M.K., Grall, A., Hédan, B., Dréano, S., Seguin, S.J., Delattre, D., Thomas, A., Galibert, F., Paulin, L., Lohi, H., Sainio, K., André, C.: Ancestral T-box mutation is present in many, but not all, short-tailed dog breeds. J Hered 100:236-40, 2009. Pubmed reference: 18854372. DOI: 10.1093/jhered/esn085
Further information is available at the Online Mendelian Inheritance in Animals website.