Bind with dogs is damn strong and even stronger when the link is built when you're vulnerable.

During these moments, they seem to fill all your emptyness by their simple contact, as if they were feeling your inner wounds... Rest of the time they only ask for attention and love in return.

Your little guy seems really healthy :)

I've seen my own old pal starting to decline a 3 or 4 years ago...
I decided to adopt another dog while he was still here, thinking that he'd help me in the newcomer's education.
It was a younger female.
Since she's here my old dog has rejuvaneted, 13years old but acting now like a youngster and seems younger than ever :p

Don't think about his death, just go on giving him a nice life and go on having a nice one too. This little guy won't ask for better than that ;)