Dr. Trépanier is best known as a breeder and importer of Ayrshire cattle and Belgian horses. He served as president of the Ayrshire Breeders’ Association of Canada on two occasions, 1936 and 1966, and as secretary of the Canadian Belgian Horse Breeders’ Association for 39 years.

As Deputy Minister of Agriculture for Quebec for 11 years, he established the Quebec Artificial Insemination Centre, introduced calf hood vaccination to the province, and more aggressive apple marketing programs. During this period he organized provincial-federal meetings dealing with national policies, as well as provincial.

Dr. Trépanier was very influential in the establishment of the veterinary school at St. Hyacinthe and later was awarded an Honourary Doctorate in Veterinary Medicine by the University of Montreal.

In addition to serving as mayor of Oka for 12 years, he has judged dairy cattle at the Royal Agricultural Winter Fair, Canadian National Exhibition and the Quebec Provincial Exhibition.