The family who own the stables where Tetley lives have had two GDs in the years I've been going there. Silk, the first one that I knew there was friendly but reserved with visitors to the yard. She wasn't possessive but she wasn't going to have any nonsense on her territory. She patrolled the yard at 10pm every night and if she thought you shouldn't be there she would stand in front of your car, refusing to let you leave until you gave a satisfactory account of yourself. The current one is a lollopy daft girl - anyone's for a cuddle and would show the burglars where the silver's hidden. Both were huge and needed a lot of exercise which, of course, having the run of the yard and a large area for walks off the lead they get. I've seen the current one running alongside the quad bike in the fields and keeping up.
Judging by those two, GDs have a good temperament but, like all dogs (and horses) if they don't know the rules they will be badly behaved and, at that size, dangerous. Kind but firm is the way to go as with all animals (including children )
Also, like all big dogs they don't live an enormously long life. I think Silk was about 9 or 10 but that was said to be an advanced age for a GD.
In the UK docking dogs tails and clipping their ears is illegal but I gather that both are still permitted under American law.
Great Dane - Wikipedia, the free encyclopedia
Not on my watch, I don't believe in declawing cats, either.