Rachel L. Dunagin, MD. Board Certified. Internal Medicine. Dr. Rachel Dunagin is a true Texan, born and raised in Dallas, a graduate of Lake Highlands High School. She is a board certified Internal Medicine physician. Dr. Dunagin obtained her undergraduate degree in Biomedical Science (magnum cum laude) at Texas A&M University at College Station.Patient Portal‧Meet Laura Harger, PA.