Short tail / Bob tail

The genetic cause of congenitally short tails was identified for the first time in Pembroke Welsh Corgi breed (Haworth et al. 2001). Further researches have proven the identical molecular reason of the congenital short-tail phenotype in other 17 breeds (Hytonen et al. 2009).

It has been found that the short-tail phenotype is caused by the mutation C189G in exon 1 of T-gene affecting the DNA-binding ability of T-protein. Dogs carrying the mutation in T-gene have natural short tails, but can differ in many respects. Some dogs have no tail and some have only half tails.

The naturally occurring short-tail phenotype has dominant expression. The mutation C189G in heterozygotes has been proven in all below stated breeds. In homozygous animals, the mutation is lethal already in the embryonic period due to serious rachisisis. After crossing two heterozygous animals, about 30 % decrease in the litter size was observed. (Haworth et al. 2001; Indrebø et al. 2007).

According to Hytonen et al. 2009, the mutation in T-gene is responsible for the short-tail phenotype in these breeds:

Australian Shepherd
Austrian Pinscher
Australian Stumpy Tail Cattle Dog
Bourbonnais Pointer
Brazilian Terrier
Brittany Spaniel
Croatian Sheepdog
Danish/Swedish Farmdog
Jack Russel Terrier
Karelian Bear Dog
Mudi
Polish Lowland Sheepdog
Pyrenean Shepherd
Savoy Sheepdog
Schipperke
Spanish Waterdog
Swedish Vallhund

.

In other six breeds characterized by naturally occurring short-tail, the C189G mutation has not been found. As to these breeds, the genetic causes of this short- tail phenotype are being investigated. We do not recommend this test for identification of natural short tail in breeds as follows:

• Boston Terrier
• English Bulldog
• King Charles Spaniel
• Miniature Schnauzer
• Parson Russel Terrier
• Rottweiler

.

References:

Haworth K. et al.: 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., Mamm Genome. 12:212-218., 2001

Indrebø A. et al.: A study of inherited short tail and taillessness in Pembroke Welsh Corgi. J Small Anim Pract. doi: 10.1111/j.1748 -5827.2007.00435.x, 2007

Hytonen et al.: Ancestral T-Box Mutation Is Present in Many, but Not All, Short-Tailed Dog
Breeds, Journal of Heredity: 100(2):236-240, 2009