Ear cropping is illegal in the UK so I am certain Labrador_Lover is asking about tail-docking which is, I am sorry to say, still legal here.

I heard people years and years ago started docking tails of dogs so that when they were hunting, the animal the dogs were hunting didn't have anything easy to grab onto.
That is partly true, the reason was, and is still, given for docking tails, that it prevents retrievers and hunting breeds getting their tails damaged when going through thick cover, brambles bushes etc.
.... some breeds like the Boxer are very excitable (would you rather have a tail docked than having to have an injured tail amputated later on in life?)
I have to disagree with very excitable being a reason to cut off a tail! These beautiful Boxers seem to be happy and healthy with their tails still intact!



As you all may have guessed I am against docking.
Chris