LAUSR

The most numerous animals in U.S. research are also the most invisible. Mice and rats comprise the vast majority of lab mammals, yet no one knows exactly—or even approximately—how many are used in scientific experiments every year. Now, for the first time, someone has attempted to calculate this number using data from U.S. labs, and it9s big: Nearly 111 million mice and rats are used annually in U.S. biomedical research, according to a new study. Some say the number argues for more federal protection for these animals, but others question both the number and the validity of the study itself.