Here is the link to the story about the blind dog and his seeing eye dog...
Blind dog and his seeing eye dog rescued in San Bernardino
I heard a similar stories...one involving 2 mastiffs and the other was with 2 horses. I recently got my senior dog a pal...not because he was going blind, but because he was becoming having health issues and he was becoming less active. I figured a younger dog might keep him going...and it has really helped in more ways than I imagined.