All animal research conducted at the ICVS in its Animal Facilities Unit is in compliance with the Portuguese and European laws (Decreto-Lei 113/2013 de 7 de Agosto; Directive 2010/63/EU) that rule the use of animals in research. Therefore, at ICVS animal research is accepted whenever it is justified on scientific, ethical and legal grounds. We follow a culture of care and apply the 3R’s of Russel and Burch, namely the replacement of animals by alternative non-animal methods whenever possible, the reduction of the number of animals used to the minimum possible (statistically supported), and the refinement of procedures to improve animal welfare. An Animal Welfare Body (ORBEA EM/ICVS-I3Bs/3Bs) revises all research proposals advising to improve the 3 Rs application in each case. The reviewing process addresses the importance of animal use for the proposed research, and whether alternative methods have been considered; the justification of species/strains as well as the number of animals involved; the procedures to be performed, level of suffering, processes to minimize it, and humane endpoints to be applied; and husbandry conditions.