I've meet quite a few GSDs and Mals with their tails docked. I believe this is done on many PSDs overseas to prevent injury to the tail (ie- bad guy grabs tail and breaks it).
I've also seen kennels dock the tails of their dogs to prevent the dog from spinning and whacking the end of it's tail off in the pen. I've seen a lot of these too, the dog will get so excited, will SPINSPINSPINSPINSPIN until it busts the end of it's tail open and then it bleeds all over. I saw one PSD in a vet clinic a while back that spun so much in the back of the car during a traffic stop that he broke his tail off.
I've also seen kennels dock the tails of their dogs to prevent the dog from spinning and whacking the end of it's tail off in the pen. I've seen a lot of these too, the dog will get so excited, will SPINSPINSPINSPINSPIN until it busts the end of it's tail open and then it bleeds all over. I saw one PSD in a vet clinic a while back that spun so much in the back of the car during a traffic stop that he broke his tail off.