Natural Bobtail

Quick Summary

Natural bobtail is a naturally occurring mutation in the T-box gene resulting in a shortened tail.

Pembroke Welsh Corgi displaying bobbed tail
Natural bobtail in a Pembroke Welsh Corgi

Phenotype: Dogs with natural bobtail have naturally bobbed (shortened) tails. Length of the bobbed tail is variable; some individuals may have nearly full-length tails while others may have virtually no tail.

Mode of Inheritance: Autosomal dominant

Alleles: N = Normal (no natural bobtail), BT = Natural bobtail

Breeds appropriate for testing: Australian Cattle Dog, Australian Shepherd, Austrian Pinscher, Bourbonnais Pointer (Braque du Bourbonnais), Brazilian Terrier, Brittany Spaniel, Catahoula Leopard Dog, Croatian Sheepdog, Danish/Swedish Farmdog, Jack Russell Terrier, Karelian Bear Dog, McNab, Mudi, Pembroke Welsh Corgi, Polish Lowland Sheepdog, Pyrenean Shepherd, Savoy Sheepdog, Schipperke, Spanish Waterdog, Swedish Vallhund

Explanation of Results:

  • Dogs with N/N genotype do not have this natural bobtail variant. They will most likely have normal length tails, though other genetic factors may affect tail length. They cannot transmit this natural bobtail variant to their offspring.
  • Dogs with N/BT genotype are expected to have a natural bobtail. They may transmit this natural bobtail variant to 50% of their offspring. Matings between two N/BT dogs are expected to produce 50% puppies with natural bobtail and 25% puppies with the embryonic lethal BT/BT genotype (an expected 25% reduction in litter size).
  • Dogs with BT/BT genotype are expected to terminate development in utero (embryonic lethal); this genotype is not expected to be seen in live dogs.

$45 one test per animal
$65 two tests for coat color/fur type/bobtail (same animal) (excludes Cocoa)
$85 three tests for coat color/fur type/bobtail (same animal) (excludes Cocoa)
+ $15 each additional test if ordering more than three coat color/fur type/bobtail tests on the same animal (excludes Cocoa)

Additional Details

Jack Russell Terrier puppy with naturally bobbed tail
Natural bobtail in a 3-month-old Jack Russell Terrier puppy

Natural bobtail (NBT) is a naturally occurring mutation in the T-box gene resulting in a shortened tail. The mutation is inherited in an autosomal dominant fashion with both sexes being equally affected. This mode of inheritance means that presence of one copy of the mutant gene will produce the bobbed tail phenotype in males and females. The length of the bobbed tail is variable and under the influence of other as yet undetermined genetic factors that cause some NBT individuals to have nearly full-length tails while others may have virtually no tail. While heterozygous individuals (possessing one normal and one affected T gene) have shortened tails, data suggest that the homozygous condition (possessing two copies of the affected gene) is lethal in utero. Breeding of two carriers is predicted to produce 25% homozygous affected offspring thus a 25% reduction in litter size.

Genetic testing is recommended to verify and validate the natural bobtail status of dogs, especially if docking is allowed, and to help with breeding pair selection to eliminate the risk of reduced litter size. Testing for Natural Bobtail assists owners and breeders in identifying dogs that have this trait.

Turnaround Time
2-6 business days



Type of Test

Results Reported As
Test Result Natural Bobtail
N/N Normal. No copies of the NBT mutation.
N/BT Natural bobtail. 1 copy of the NBT mutation.
BT/BT Natural bobtail. 2 copies of the NBT mutation.*

* Result unlikely to occur for live dogs; NBT is considered a homozygous lethal in utero.


Haworth, K., Putt, W., Cattanach, B., Breen, M., Binns, M., Lingaas, F., & Edwards, Y.H. (2001). 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(3), 212-218. 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. (2009). Ancestral T-box mutation is present in many, but not all, short-tailed dog breeds. Journal of Heredity, 100(2), 236-240. doi: 10.1093/jhered/esn085