Owning a Rottweiler for many years, I do believe the tail is docked due to the fact that they were bred to be herding & guarding, and the tail most likely was in the way. I do believe now, that the AKC, recognizes the Rottie with the tail not docked is acceptable for show. Not sure but I think the European Rotts allow the long tail, and docking is not required for show. Both the long and short of it, they are both acceptable in showing.
Debi

its for their breed standards…..DOCKING OF TAILS and CROPPING THE EARS is so cruel

AKC/UKC/CKC standard, and most think it looks better as well. Personally I prefer the look of the dog all natural, as well as with Doberman’s.

Some horrible people fight dogs and they usually do it so they don’t get bitten their. Some do it because they had something wrong with their tail. Some people do it because they think it looks better.

The main purpose is tradition and the look. Rotties used to have their tails docked so when they went to fend off someone, that person would not have a tail to grab onto and then possibly gain control of the dog.

It’s traditional for some breeds. The natural tail is likely not very attractive. In some breeds, they wag it so vigorously that it’s likely to be injured. If the docking (tail cutting) is done when they’re young enough, the trauma is over quickly and with very little risk.

I think it’s because they are herding and guard dogs and they dock the tail so it doesn’t get hurt in a fight. I think dogs with docked tails are ugly. No offense to people who like it but when I see a dog like a dobie or rottie I sort of expect to see a nice long tail to match, but all that’s at the end is this ugly little knob.

So they won’t bite it off and hurt themselves. They also look cuter like frech poodles.