There are quite a few older dogs listed. But isn't that pretty typical? People get married, have a baby, move...and decide they don't have time anymore for their once-upon-a-time best friend. Or they get sick of their puppy when said puppy grows up
It's so sad. I always get teary-eyed when I look through the rescue listings, or Petfinder. It makes me realize how much I take for granted. I only hope that all of those pups find a home as loving as the one you've made for sweet Tuppance.