A native of Montreal , Canada , Maurice Vachon had a very successful amateur wrestling career. He won three national titles in Canada and was a member of the Canadian 1948 Olympic team, placing seventh in the 174-pound class while just eighteen years old. In 1950, he won a gold medal at the British Empire Games.

Shortly after, Vachon gave up his amateur status to turn professional and enjoyed a pro career that lasted nearly four decades. He adopted the name "Mad Dog" while wrestling in the American Wrestling Association (AWA) with Verne Gagne, and became a top draw worldwide.

Vachon was world heavyweight champion for the AWA on four different occasions. He also was half of the tag-team world champions, pairing first with his brother, Paul Vachon, and then later in his career with Verne Gagne. Maurice's sister, Vivian, was also a world-class women's wrestler.

In the late 1980s, Maurice wrestled in the WWF for a while. He retired in Montreal in September of 1986 at the age of 57, amid great fanfare.