Shiroi Senshi Yamato(1976)

Shiroi Senshi Yamato

Ryou, a kindhearted boy living in a small mountain village in Yamagata. Yamato, the son of the legendary fighting dog Fubuki, whose name once echoed throughout the nation. Together, this boy and his dog step into the brutal world of dogfighting! The masterpiece by Yoshihiro Takahashi that served as the precursor to Ginga: Nagareboshi Gin! The fiery legend of dogfighting begins now!!

(Source: Shueisha, translated)

Note: Includes the one-shot "Moon Kid"