I lost my 18 year old Pomeranian last fall.
She had cataracts for the last couple of years started being afraid to go up and down steps because she couldn't see them. she would jump from the top step.
My 16 year old beagle/border collie mix has them now also but they hide it well you'd never know it unless you watch her close.
We walk a mile a day at the park and I believe that has contributed to the longevity and good health of these dogs.
At the park she used to run through the woods now she stays on the path and within sight of me.
My 9 year old long haired 70 lb Bassett mutt is now the puppy of the family.