Opinion paper: Improving experimental design in animal research-seven key principles

Robust experimental design is essential for reliable and reproducible animal research. Yet, researchers indicate that critical challenges in experimental design persist. Common issues include confusion between experimental and observational units, inadequate sample sizes, incorrect statistical analyses, and the absence of randomisation, or blocking. These shortcomings not only compromise the quality, reliability, and reproducibility of research findings but also risk wasting resources and animals (Resnik and Shamoo, 2017, Rowe, 2022).
To address these challenges, recent initiatives within the PIGWEB project (funded by EU Horizon 2020) have developed comprehensive guidelines highlighting seven key principles for improving study design (De Cuyper et al., 2025). Although initially tailored for pig trials, these principles are broadly applicable across species and research contexts, providing a framework to enhance the data quality of animal studies.