i have a rottie male and a chinese crested bitch, and the male is 4 and the chinese crested is 18 months and they get on great if anything the amount of times our crested gets told off for having a go at the rottie, he is very gentle with her, but we where very carefull when we got her, as he does not realise that he has a body from the neck down, there was only a couple of scary incidents, he sat on her once but she screamed the house down he sharp got up and once when she tried to race him to the front door he nearly squashed her but she squealed again and he stopped, when we take them out together we tend to pick her up through the front door just incase in the excitment of going out he hurts her, they sleep together and she eats out of his dish and he waits until she is finished and then eats,you just have to be aware of the size difference and the damage your dog can do, unintenionally.
and you will proberly find the little one will think it is a big dog also.
carol