Congrats Marebear & family!! You guys will love him.  We have had our Dane girl, Charlemagne, since she was a pup and she just celebrated her 12th birthday!!
 So your guy may just be middle aged.
Two years ago on Christmas eve we got a call from our local rescue group asking us to go pick up two Danes that people had left tied to the front trees when they were evicted.   We skipped church and drove right over to find a very skinny, young,  male and female black Great Dane tied to the trees as reported.  
 We loaded them in the car and took them home, they were super sweet and we started slowing feeding them back to their proper weight....however, it soon became apparent all of the females food was going right to her middle, so we started her on calcium and extra vitamins and sure enough two weeks after we picked her up she gave birth to 11 Great Dane puppies!!!!  They all made it fine.  We supplemented them with goats milk and they all did great.  Boy, it was a crazy time with our own two Great Danes, plus the mom & dad and then 11 puppies, we had 15 Great Danes at our house 
  That was two years ago and they have all since been spayed/neutered and adopted out to wonderful families...even the parents, however it is an experience that I will not soon forget!!  Since I had always done dog rescue I had never had a litter of pups born at our house, or even helped with any being born....boy, was that an experience in itself!!  
So, without wonderful people like you and the family willing to adopt I would still be here with 11 two-year-old Danes....oh my and I thought the puppies were alot of work!!!
Enjoy him, I know he will bring a lot of happiness to your family!