I have 2 full grown lab's (not close to as big as a Dane LOL) each about 60-65lbs and my Yorkie who is still a pup is just 2lbs now. My husband also got a new pup at the same time, same reasons the Yorkie is just to girlie for him. So we have a 17wk old Boston terrier who is just awesome and very manly.
I'm assuming you have always wanted a Dane and thats why you are choosing that breed so as long as you do your research and if you do get it as a puppy make sure that you are very careful with the 2 of them together so that the Yorkie doesn't get hurt which could happen easily with as small as she is I would go for it. My 10month old lab and our little dogs play together very well, she is still a puppy herself but seems to "know" that Bella is tiny and is very very gentle with her.