How's that story go? The one where the little girl asks her daddy why dogs don't live very long? Why they can't stay longer with them? Her father asks her what she thinks the answer is and she says - "I think that we live a lot longer than dogs because we have a lot to learn. Dogs already know the answers so they can go to Heaven sooner." Or something like that..........
Problem with wanting a dog that lives for a long time is that no one would want the same breed of dog. Then you would have to start fooling around with the genetics of all dogs. While it is an interesting theory why can't we be happy loving our pets for as long as we are graced with their wonderful presence and leave it at that? The mere thought of the number of dogs that would be culled for our own selfish reasons is mind boggling.