Sylvain De Guise obtained his veterinary degree (DMV) from the Université de Montréal in 1988. After a year in private veterinary practice (mostly small animals), he then pursued a veterinary pathology residency combined with a Master's degree on the pathology and toxicology of St. Lawrence beluga whales, also at the Université de Montréal. He then pursued a PhD investigating the possible effects of environmental contaminants on immune functions of marine mammals, also in relation to St. Lawrence beluga whales, at the Université du Québec à Montréal. After a post-doctoral fellowship at the University of California, Davis studying in more details the immune system of marine mammals, he accepted a position of Assistant Professor at the University of Connecticut in 1998, where he was recently promoted to the rank of Associate Professor.

The transition between veterinary medicine to pathology, toxicology and then immunotoxicology was one that was led by the findings of previous investigations, the discovery of new exciting fields and the passion to uncover complex environmental mysteries.