You may find that the decision is taken out of your hands and she may die naturally in her sleep, so be prepared for this too.
I have always found when animals go off their food and are reluctant to go out then they are getting near the end.
Keep a close relationship with your vet (the brown urine could be a kidney infection?), they will let you know if your dog is in any pain. If she is not and you are able to keep her clean and happy then I would not do anything. All dogs (like people) are different, I had a GSD in a K9 cart for 18 months, she was quite happy even though she was paralysed, I have had other dogs I would not even consider putting in that situation. I too was told that she had lost her 'dignity', but they did not know my dog - dogs live for today, they do not think about what tomorrow will bring, as long as she is showing interest in things and getting around OK then I would be happy. Believe me, when an animal gives up you know about it!
Spoil her in her remaining time with you, she is a good age for a Dane and sadly what will be will be, just remember that you do the best you possibly can at the time, there are lots of us here that understand and have been through the same thing.
Thinking of you.