Dr. St. Denis is a practicing feline medicine specialist, board certified with the American Board of Veterinary Practitioners in the specialty of feline practice. In her early career she trained in molecular biology and immunology, working in the field of cancer research. In 1999 she graduated from the Ontario Veterinary College, going on to own and operate the Charing Cross Cat Clinic from 2007 to 2020. Dr. St. Denis is the 2020-2021 president for the American Association of Feline Practitioners and an active volunteer in the organization, participating in many committees and task forces. Dr. St. Denis is a consultant on the Veterinary Information Network in feline internal medicine.