Trends in Animal Use at US Research Facilities

Background:  Minimizing the use of animals in experiments is universally recognized by scientists, governments, and advocates as an ethical cornerstone of biomedical research. Yet, despite growing public opposition to animal experimentation, mounting evidence that animal studies often do not translate to humans, and the development of new research technologies, a number of countries—including Canada, Australia, Israel, the United Kingdom, and Germany—have reported increased animal use in recent years. In the United States (US)—the world’s single largest user of animals in experiments—a lack of readily available data on the species most commonly used in laboratories (i.e., mice, rats, and fish) have previously limited such analyses. Methods:  Animal use data were obtained from Animal Welfare Assurance documents filed with the US National Institutes of Health (NIH) by the top 25 federally-funded research institutions. To assess changes in animal use over time, copies of the three most recent Assurances from each facility were acquired through open records requests. This study analyzes the use of all vertebrate animals by these institutions over a 15-year period ending in 2012. Four institutions were excluded from our analysis as complete data were not available for them.  Results: The total number of animals used at the 21 institutions increased 72.7 percent over the 15-year period studied. A repeated measures ANOVA indicated this increase was statistically significant, F(1,20) = 6.7, p = .018. Planned comparisons between individual time points found a significant increase in total animal use between time points one and two, t(20) = 3.52, p = .002, as well as between time points one and three t(20) = 2.58 p = .018, though not between time points 2 and 3, t(20) = .470, p = .644. Post-hoc analyses revealed that only the increased use of mice was statistically significant, F(2,36) = 4.84, p = .014. Only one species (cats) showed a consistent decrease in use over time, but that decrease was only marginally significant, F(2,36) = 2.96, p = .063.  Conclusions: Despite institutional commitments and government policies to reduce the use of animals in experiments, our data show the use of animals has grown significantly—driven primarily by increases in the use of mice. Greater efforts are needed to provide transparency of and curb animal use in laboratories.