
Natural bobtail

A natural bobtail is an animal's tail which due to a mutated gene grows unusually short or is missing completely. The genes for the shortened tail may be dominant or recessive.
Because of legislation restricting or preventing docking, natural bobtails are growing in popularity among the dog fancy for some traditionally docked breeds. For example, one Boxer breeder and geneticist in England has successfully petitioned the Kennel Club for permission to cross Corgis into his lines and then backcross to Boxers, introducing the gene into his lines. This would have been unheard of in decades past. A number of these bobtail Boxers have been exported to various countries around the world.
However there are some breeds, the Rottweiler for example this NBT are not recognised as accepted in the Country of Origin Breed Standard. Whilst it is in countries such as Australia.
Animals with a natural bobtail.
Cats.
More than one gene is responsible for tail suppression in cats; research is incomplete, but it is known that the Japanese Bobtail and related breeds have a different mutation from that found in the Manx and its derivatives.
Experimental breeds (mostly cross-breeds of the above):
Dogs.
A mutation in a gene called the T-box transcription factor T gene (C189G) accounts for natural bobtails in 21 dog breeds, but not in another 5 breeds, for which the genetic mechanism is yet to be determined.
One study found 17 of 23 newly studied breeds had the gene, in addition the Pembroke Welsh Corgi identified in previous research. This study counted Rottweilers as not as not having the C189G gene, but tested only five Rottweilers, only two of which were short-tailed dogs. Another study showed that Rottweilers do carry the gene, and Dobermanns (not tested by the earlier study) do as well. 
Natural bobtail dog breeds with C189G mutation:
Natural bobtail dog breeds without C189G mutation: 
Dog breeds into which the C189G mutation has been introduced by cross-breeding:
Dog breeds where natural bobtails have not yet been tested for C189G mutation:
Breeds in this sub-list often have full tails.
References.
5. https://www.orivet.com/store/canine-trait/natural-bob-tail-short-tail-phenotype-
6. https://www.animalnetwork.com.au/tests/index.php?testid=14
7.http://www.vetbook.org/wiki/dog/index.php/Natural_bob_tail