Great Danes usually don't live terribly long because when they were originally bred their heart cavities weren't big enough to support their hearts for a long time. Their general lifespan is only about 8 years.
Well,like all the other dogs,if it's feed well and yout ake care of him wel,can live upon 10-15 years. Of course when he gets old he tires more often and he will not have the same energy he used to have
The average would be seven to ten years depending on how it is treated and razed and whether you live in the country or city. The best thing is to take care of him or her carefully watch what they do and never just let them go out in the woods if you live in the country.
i got a girl great dane called croft there life span is not long but they are very big heavy dogs and can pull on a lead they dont like being picked up cause theyre to big theyre are very clumsy and lazy they act like there small