BOBCATSHOPPER asks: "I have Great Dane/Lab mix. He's a great dog, but he's got a tail that is like a whip. We do what we can to keep him calm, but it's impossible to keep a dog from wagging his tail. It hurts when his tail hits the guys in a sensitive place, and he's smacked the kids across the face a few times. We're considering getting his tail cropped/docked, but we don't know if there is an age limit. We would leave his tail alone if it wasn't hurting anyone, but it is. My daughter has already gotten one black eye from being whacked with his tail..." full forum post
Update March 2011:
This 2006 blog post has generated good discussion about tail docking in dogs. There is an important distinction between cosmetic/elective tail docking surgery and medical reasons (e.g. repeated or non-healing tail injuries) for tail docking.
You are invited to submit your stories and opinions about tail docking in dogs in our new Reader Responds section.