The Poisoned Waterhole - S1.E12

Gene trains Champion for a jockey, Corky, who will ride the horse in a race. Hap Wallace (Pat Buttram) and Corky rude into town to enter Champion in the race. Along the way, Hap runs into some outlaws, who take him into racing Champion against on of his gang member's horse, Midnight. Hap of course bets on Champion. When the race comes, Champion falls ill, and Midnight wins. Hap and Corky discover that the race was fixed, and are captured by the outlaws. Corky is able to escape, and goes to Gene, who rescues Hap, while Corky forms a false posse. When the coast is clear, the outlaws break into a safe that contains Indian funds. Gene captures the outlaws, and tends to Champion.