Stormy by Jim Kjelgaard

Dog books - Stormy Allan and Stormy, his black retriever, are left alone in the forest when his father is abducted.
Allan Marley and his father have spent their whole lives together in the Beaver Flowage's untamed nature. However, when Mr. Marley is imprisoned as a result of a nasty dispute, Allan finds himself on his own. Then he encounters Stormy, an outlaw dog suspected of betraying his owner. Allan is well aware that the noble dog has been abused, and he tries tirelessly to earn the noble dog's confidence and devotion. Allan and Stormy conquer every peril they face in the unforgiving woods as partners... but will their relationship shield Allan from the ruthlessness of his father's human foes? Stormy by Jim Kjelgaard