Dr. Fitzsimmons is a native of Baltimore, Maryland. She received her undergraduate degree from Loyola College and Doctorate of Veterinary Medicine from Ohio State University. Dr. Fitzsimmons moved to St. Mary's County in 1993 and joined VCA St. Mary's Animal Hospital.

Dr. Fitzsimmons has a special interest in the care of small mammals. She also has a special interest in feline medicine and geriatric medicine.