White Fang.

A gray wolf raised on a farm kills the family dog, and to save him from being destroyed, a boy named Lasset makes a trek through the wilderness with the wolf to a wilderness sanctuary 300 miles to the north. The BGM in the film consists entirely of Dvorak's Serenade for Strings, making it perhaps the only anime since Gauche the Cellist to make use of a single piece of classical music as the soundtrack. The plot of the film is simple and the outcome obvious, but the atmosphere of the film is genuine, and it is very moving in parts thanks to Dvorak's music (which is scored entirely for the most emotional of the instrument groups, the strings). This is a straightforward drama about the friendship between a boy and his wolf, and it pushes all the buttons you'd expect, but it's very enjoyable despite all that.