It does sound like incontinence - the same thing happened to my mom's dog at age 15 - he literally had no control and we did end up having him PTS (he was also going blind and my mom was an invalid as well). I doubt that it's anything that your dog is doing on purpose - my understanding has always been that dogs don't think that way.
Riley - 8 yr. old GSD
Schatzie - GSD - at the Bridge
Raven - GSD - at the Bridge
Diablo - WGSD/Arctic wolf/GreatPyr Mix - at the Bridge
If dogs aren't in heaven, why would we want to go there?