Sprague - Dawley rats have a lifespan of about two years .
Sprague - Dawley rats have a high risk of cancer over their lifespan ( one study concluded that over eighty percent of males and over seventy percent of females developed cancer under normal conditions ) .
Sprague - Dawley rats have a lifespan of about two years and have a high risk of cancer over their lifespan ( one study concluded that over eighty percent of males and over seventy percent of females developed cancer under normal conditions ) .