Cross Breeds - what is the story about a young boy who led a sled dog and after the race the dog died?

what is the story about a young boy who led a sled dog and after the race the dog died?

i remember reading this in like 5th grade and I loved it...but i'm not sure what the book was called.

You may be thinking of Stone Fox by John Reynolds Gardiner. I have used this book for my 4th and 5th grade classes for years.
Probably Stone Fox. But the dog dies right before the end of the race and the boy carries him over the finish line. I sobbed. Fairly embarrassing in the middle of class. But that is a great book!