4R Rule in Laboratory Animal Science

In vitro models that can completely mimic the complexity of the human organism are still not available today. For this model, laboratory animals are often used as a living organ complex. Laboratory animals are used in basic medical sciences, to test the safety of medicines and chemicals, and for training purposes. The basic principles considered in laboratory animal science are defined as replacement, reduction, and refinement. Nowadays, “responsibility” is added as the fourth principle. Thus, 4R concept was formed. In this article, it is aimed to give detailed information about these four concepts.