Today I had a very nice walk with my two guys and a friend and her dog. It was the first time I saw my older one having a bit of a difficult time. He was walking slowly and pausing quite a bit. At two points I had to pick him up to give his legs a rest.
He has luxating patella in both back legs which up until recently wasn't a huge issue. I see now the arthritis must be getting worse and mobility is an issue.
I suppose there is no good way to prepare for the slowing down of your "heart" dog. It's just difficult to watch.