That Corgi butt, which in most Pembroke Welsh Corgis comes with that fantastic natural bobtail, a result of a mutation in the... (embarkvet.com)
Breeding two dogs with natural bobtails will result in slightly reduced liter - sizes because about 25 % of the puppies will inherit two copies of the T Allele and will die In Utero. (pawprintgenetics.com)
The ASCA standard describes the tail as «straight, not to exceed four (4) inches natural bobtail or docked.» (ashgi.org)