Animal Models: Mouse Is King

Mice and rats are go-to animal models for research. A recent report out of the European Union demonstrated the dominance of these rodents in research. A count of every laboratory vertebrate in 2008 revealed that mice and rats made up nearly 80% of the 12 million animals used for research in the European Union.¹ When those numbers are broken down further, we find that mice are more popular than rats: globally, some 52 million mice are used annually, compared to 15 million rats.² So, why do mice dominate scientific research?

The history of the mouse as an animal model dates back to the early 1900s.³ The lab mouse found its beginnings in the fancy mouse trade. People would collect, breed, and sell mice with different coat colors. One of those fanciers, Miss Abbie Lathrop, was also a scientist. She carried out experiments in collaboration with two scientists at Harvard: William Castle and C.C. Little. Working with their new animal model, they studied and published findings on coat color genetics, hormonal regulation, and cancer. Many of the early inbred strains of mice they worked to create went on to become founding mice at The Jackson Laboratory, a research facility and warehouse of animal models.

From these humble beginnings, the mouse picked up steam to become the primary subject of animal model research. There are a few factors contributing to the overwhelming popularity of the mouse as an animal model. Some of it is cost: mice are relatively inexpensive to house and breed. Some of it is a positive-feedback loop: previous work uses mice, and so goes future work. And some of it is the vast array of genetic modifications that have been made to mice. This deep library of mutants allows for animal models that mimic various aspects of human disease, including cancer, blindness, neurological disorders, and more.