She previously served as the chair of the Dept. of Animal Science at Michigan State University and spent 20 years as a Professor and extension milk quality specialist in the Dept. of Dairy Science at the University of Wisconsin, Madison were she remains an emeritus Professor. Dr. Ruegg has academic degrees from both Michigan State University and the University of California, Davis. She has had varied professional experiences including private veterinary practice, academic positions at both Atlantic Veterinary College in Prince Edward Island, Canada, and the College of Veterinary Medicine at MSU and corporate technical service. Her areas of expertise include preharvest milk quality and safety in dairy cows, udder health and antimicrobial usage on dairy farms and assessment of milking performance and dairy animal health records. She maintains a research program that is focused on ensuring antibiotic stewardship on dairy farms by reducing antibiotic usage on dairy farms and identifying cow, environmental and pathogen factors that can be manipulated to reduce mastitis risk. Dr. Ruegg is active in a number of industry organizations and is a past-president of the National Mastitis Council. Her extension program has focused on developing programs that help farmers maintain healthy cows while reducing antimicrobial usage and improving milk quality and safety on dairy farms.

Throughout her career she has received a number of awards for research, extension and international outreach programs and she has published numerous peer-reviewed articles that are frequently cited.