Personally I'm a little torn about bringing kids to this film. So I'm pleased to hear that your focus group of eight-year-olds liked it, Sam! It's a positive film...but could be rough on some young ones.
I've given this some thought.
One of the obvious reasons I was concerned about kids seeing it is the obvious reason:
the very sad scenes involving the deaths of the dogs.
However, one of the things I said to my wife as we were exiting the theater (because those sorts of scenes really have an impact on her, too) is
that they didn't linger after those by quickly introducing the new puppy (with which we got to continue on the adventure). I think that quick turnaround each time made those unpleasantly sad moments bearable (for young and old alike). It's not an easy thing to accomplish.