My Pal Trigger
Taken from IMDB : Gabby refuses to breed his horse the Golden Sovereign with Roy's. When the Sovereign and Roy's horse escape, Skoville shoots the Sovereign by mistake but Roy is blamed and jailed. A year later Roy returns with Trigger, the son of the Sovereign. When Skoville slips and reveals he was present when the horse was shot, Roy sees a chance to clear his name.