Hi! Its always fun to walk for a cause.  Here are the things you might want to consider. How old is Duke now and how far does he normally walk on a daily basis? If 2 miles is substantially more than he normally walks then you might not want to do this, even if he is in good shape.

For comparison, we have three rear leg amp GSDs. Austin, at 5, is the least physically fit (he has elbow and hip dysplasia and arthritis so all his remaining limbs are affected). A half mile walk is best for him although he would keep going as long as he can. I have taken him on 1.5 mile walks occasionally and he can do it but it is really too much (e.g. his rear foot starts to drag towards the end). Travis at 6 does 2 miles easily, he is big and strong and in his prime. Codie Rae at 5 could easily walk 2 miles, at 7, she got alternating daily walks of 1 mile and 2 miles, at age 9 (she is going on 10 this year) we cut her back to one mile daily walks and now she even gets a day off now and then and doesn't seem to mind at all.

You know Duke and his abilities best. If you have any questions about his ability to complete the walk then maybe you could enter but monitor him carefully and be prepared to pull him out of the walk if he is showing signs of being tired.

Hope this helps!

Martha, Codie Rae, and the Oaktown Pack