Experimental Animal Use in Spain and Europe: Trends and Statistical Insights

This study provides a comprehensive analysis of experimental animal use in Spain (2009-2023) and the European Union (2015–2022), across research fields, disease models, and species. Between 2009 and 2013, fundamental biology dominated animal use in Spain, with notable declines after 2009. Disease-related studies showed high usage in other human diseases and cancer, while cardiovascular models increased. From 2014 to 2023, basic research remained prominent but was overtaken by translational and applied research after 2020, reflecting evolving research priorities. Human cancer remained the most studied disease model, though its use declined after 2017. Mice were consistently the most used species in both Spain and the EU, reaffirming their central role in biomedical research. Fish species, including zebrafish and sea bass, gained importance, particularly  in developmental studies. COVID-19 did not significantly alter total animal use patterns, though minor, statistically non-significant fluctuations occurred. The results highlight long-term trends, shifts in species preferences, and the need for continued efforts in reducing and refining animal use in scientific research.