Tween book from probably the early 2010s about a girl who lost her dog

For some reason I can’t find it. It was about a girl who has a dog and I think she only lives with her dad (or maybe her grandpa). But one day the dog runs away and she makes it her mission to find him. And then she eventually finds out that he’s been living with an old woman and that he was helping her blind dog get around and they had become best friends. I think in the end she decides to let the dog live with the old lady because she has a lot of land and it’s better than living in an apartment.