Cross Breeds

In what book does a racing dog's heart explode before it can finish a race?

I read a book a long time ago in which a boy trains this dog to run it in a race. He cuts across an ice lake, and he's in first place. The finish line is only a little ways away but the dog's heart explodes and she dies before she can cross the finish line. Then someone pulls out a gun (I think) and says the boy will finish first or something like that. :S What was this book, and who wrote it?

Public Comments

1. The book is Stone Fox by John Reynolds Gardiner.
2. Stone Fox by John Reynolds Gardiner.