Online software that can improve the design of animal studies is welcome, but it should not replace specialist advice (see Nature 531, 128; 2016).

Animals are complex biological systems. Their organs and tissues have variable and dynamic functions and morphology in pathophysiological conditions. This complexity calls for a holistic perspective from researchers, who can anticipate and tackle different experimental issues through all phases of a study while aiming for reduction, refinement and replacement in animal use (see www.nc3rs.org.uk/the-3rs).

Such multidisciplinary input also helps to overcome limitations in researchers' scientific scope, experience and skill sets and to improve the quality and interpretation of the results (H. A. Adissu et al. Dis. Model. Mech. 7, 515–524; 2014).