Without systematic reporting in the United States, accurate estimates of numbers of mice used are not available. Rough estimates in the United States range upwards from 6 million mice, presumably accounting for at least half of all mammals used per year. Quality of Life Induced genetic defects and research procedures sometimes cause pain and suffering to laboratory mice that may be somewhat alleviated by appropriate analgesia and anesthesia. Enhancing the quality of life for mice may partially offset some of their discomfort. For example, living in social groups would be a more normal situation than solitary housing.
Caregivers also can enrich the physical environments of mice by considering the housing.
Mice provided with hardwood shavings burrow and build nests. Placing hay or straw on racks above cages allows mice to pull material into the cage and arrange nests. Plastic tubes offer an artificial burrow space, perhaps shielding mice from illumination that may be too bright. Simple enrichments such as these can provide mice some control over their environment. One complication is that immunodeficient mice require sterile environments.