Born in Lindenhurst, NY, Feustel was only ten years old when he began working in the horse racing industry as a stable hand. At age twenty-four he became a professional trainer. He had a long association with August Belmont Jr., working as a lad at his stable and rising to the position of foreman. and head trainer. In 1913, Feustel conditioned Belmont's colt Rock View to American Champion Three-Year-Old Male Horse honors with wins in several major races including the Brooklyn Derby and the Travers Stakes. In 1914, August Belmont began winding down his racing operations and sold off a number of his runners. When the United States entered World War I, the sixty-five-year-old August Belmont Jr. joined the United States Army. While overseas he decided to liquidate his racing operations and Louis Feustel went out on his own, racing horses for himself before going to work as the head trainer for Sam Riddle'sGlen Riddle Farm. Prior to the 1918 Saratoga auction of the Belmont horses, Feustel had urged Sam Riddle to purchase a yearling son of aa August Belmont horse he was very familiar with named Fair Play. Riddle, however, was not impressed enough by the young horse and balked at buying until his wife put added pressure on him.
Relations between Louis Feustel and Sam Riddle became strained and near the end of June 1921 he made arrangements with his old employer, August Belmont, Jr., who had rebuilt his racing and horse breeding business, to prepare his yearlings for racing. Although Feustel won the May 1922 Newtown Stakes and Richmond Handicap with Sam Riddle's horses, by the end of the year he was once again training all of the August Belmont, Jr. stable. In 1924, Feustel conditioned Ladkin to his historic win in the International Special No. 2 over the European superstar, Epinard. August Belmont, Jr. died that year and Feustel was once again out on his own. In the latter part of the 1920s he began conditioning horses for newspaper publisher, Bernard Ritter and in the 1930s he trained a successful racing stable for Mrs. Elizabeth Graham Lewis. A serious automobile accident in February 1943 kept Louis Feustel out of racing for several months and in 1950, after forty-two years training horses, he retired. He and his wife eventually made their home in Pasadena, California. Following his wife's death, in the late 1960s Feustel was living with a son in Chicago. Louis Feustel died on July 7, 1970 at age eighty-six.