She continued her studies in medical technology at Baylor University Hospital in Dallas.
In the late 1950s, at Parkland Memorial Hospital, she helped develop a rape kit for collecting evidence following sexual assaults.
Guy was president of the South Central Association of Blood Banks from 1964 to 1965.
She was professor emeritus in the pathology department at the University of Texas Southwestern Medical School.
In 1973, she received the John Elliot Award from the American Association of Blood Banks.