After graduating from the École Nationale Vétérinaire de Lyon, France, in 2002, Marion Desmarchelier worked in mixed practice (small animals, equine and dairy cattle) for a year. After an internship with birds of prey at the Faculty of Veterinary Medicine of the Université de Montréal, she completed a one-year internship (IPSAV) in zoological medicine in Saint-Hyacinthe. Following her return from France, she worked for a year in a referral hospital with exotic animals and small animals, while volunteering for a wild bird care center. Marion Desmarchelier then completed a residency program in zoological medicine as well as a master's degree in clinical sciences on pain in birds. She was a Clinical Professor of Wild, Exotic and Zoo Medicine at the Atlantic Veterinary College in Prince Edward Island from 2010 to 2014. Subsequently, back in Quebec, she combined her work as a clinician in zoological medicine with a second residency, in animal behavioural medicine. Marion Desmarchelier is a Diplomate of the American College of Zoological Medicine (2009), the European College of Zoological Medicine (Zoo Health Management) (2014) and the American College of Veterinary Behaviorists (2018). She is an associate editor of the Journal of Zoo and Wildlife Medicine and was a contributor to the latest edition of the reference book Fowler's Zoo and Wild Animal Medicine.

Marion’s research interests include studying the impact of training methods on the welfare of therapeutic horses and their coregulation with children on the autistic spectrum. A long time equestrian, Marion enjoys horseback riding and ski joering with her pony mare.