There are some corgies with the "bob tail" gene where they are born with short tails. There was also an experiment done some time ago where they bred one with a boxer to get the same "bobtail" effect with out having to dock a dogs tail.
In this experiment they got a purebred boxer x Corgi litter. 2 dogs out of the litter were born with the bob tail that needed no docking. They bred these until they were able to get the boxer appearance back and with the bob tail gene. Most registries especially in Europe will not allow boxers with the bob tail gene. I wish the US had strict standards for breeding like Europe does.
Check this article out.
http://www.boxerunderground.com/1998...98/bobtail.htm