Natural Bob Tail (Short Tail Phenotype)

Test Overview:

Natural bobtail can occur in several breeds, and the gene for this seems to be inherited in an autosomal dominant fashion. When a pup has two copies of the defective gene, this is lethal to the development of the foetus and the pup will die before it can be born. One copy of the gene can result in no tail, a normal length tail, or any length of tail in between (i.e. a shortened tail). Occasionally the tail may be kinked. Very rarely there may be other developmental abnormalities, e.g. defects of the anus – although studies have not demonstrated a clear relationship between the occurrence of these defects and the bobtail gene, as they can occasionally occur in dogs without this gene as well. Studies also have shown no reduced survival of litters of Australian Shepherd natural bobtail pups compared to normal tail pups to 8 weeks, and no increased incidence of severe spinal defects as is sometimes reported. Natural bobtail litters may be slightly smaller in size, showing that the pups with 2 copies of the mutant gene are not surviving through the gestation period.


Trait (Associated with Phenotype)


Gene: T on Chromosome 1

Variant Detected:

Base Substitution C>G


It is a trait and so is tested based on preference, not usually for health concerns.

Mode of Inheritance:

Autosomal Dominant

Research Citation(s):

J Hered. 2009 Mar-Apr; 100(2):236-40. [PubMed: 18854372]

Associated Breed(s):

Australian Shepherd, Australian Stumpy Tail Cattle Dog, Boxer , Brittany Spaniel , Dobermann, Jack Russell Terrier, Koolie , Miniature American Shepherd, Parson Russell Terrier, Pembroke Welsh Corgi, Rottweiler , Schipperke, Swedish Lapphund, Swedish Vallhund, Tenterfield Terrier , Tibetan Spaniel,