The Principle of the 3Rs is widely recognised as the methodological and ethical backbone of contemporary animal research. Different authors also stress the reciprocal links among the 3Rs, and how these often complement and reinforce each other. We very much agree with this point, but in this contribution we would like to raise some problems related to the application of the “3Rs”. There is an obvious link among “Replacement, “Reduction” and “Refinement”, but it is worth to notice also that each “R” has its own conceptual characteristics, as well as its own level of applicability. For example, a realistic “methodological inertia” has to be expected more in the case of “Replacement” than in the case of “Refinement”. This also leads to a second order of issues, and here we will offer our experience as projects evaluators. The “3Rs” differ also in the possibility to verify how are applied by the proponents of research protocols involving the use of animal models. Sometimes it appears that the application of the Principle still resolves itself in the use of formulaic sentences, from which it is difficult to really understand the reality of the laboratory decisional and procedural processes. However, the demanding characteristics of the “3Rs” can vary greatly, and this is something that has to be considered. We propose that a network, or a virtual platform, of evaluators could help both researchers and evaluators for a more satisfactory understanding and pragmatic application of the Principle of the 3Rs.

Promoting good primate welfare outside of daylight hours is an important task. The responsibility to provide a complex environment and environmental enrichment is an essential element of primate wellbeing programs that should be approached from a 24-h perspective and planned according to the species and individual needs, including giving animals the ability to interact with and control their environment during hours when animal care staff are not present. One must be aware, however, that their needs may differ at night-time from their care needs during the day when staff are present. Assessing welfare and providing enrichment during times when staff are not on hand can be achieved through the use of a variety of technologies, such as night-view cameras, animal-centred technologies, and data loggers. This paper will address the relevant topics concerning the care and welfare of primates during off-hours, and the use of related technologies to facilitate and assess wellbeing at these times.

Members of captive colonies of common marmosets (Callithrix jacchus), a small New World primate, can occasionally be victims of repeated, and potentially fatal, attacks by a family-mate. This study examined the records of a colony, looking for past instances of such aggressions. The aim was to better understand the possible causes underlying this phenomenon and to identify variables that could minimize their occurrence. The results showed that both males and females behaved as aggressors at the same rate, but females attacked just females, whereas males attacked both males and females. Most aggressions involved siblings and occurred at a higher rate when the cages were occupied by more than 5 nonhuman animals. The influence of group size was significant only when females behaved as aggressors. This study suggests that several factors can determine the occurrence of these aggressions and that their relative importance depends on the sex of the aggressor. The results of this study highlight the importance of collecting further data to verify whether crowding in a confined space, rather than group size per se, affects the incidence of these aggressions.

The overall aim of the ‘Improving the Quality of Biomedical Science with 3Rs Concepts’ (IMPROVE) COST Action (CA21139) is to establish an interdisciplinary network dedicated to refining, harmonising and promoting the adoption of the Three Rs concepts, to enhance the quality of biomedical research. The ‘IMPROVE’ COST Action has assembled an Ethics Crossover Group composed of volunteer members from each of IMPROVE’s four established Working Groups: ‘Quality and translatability of science’, ‘Implementation’, ‘Dissemination’ and ‘Education’. This report relates to a two-day workshop, held in Acibadem University in Istanbul on 2–3 September 2024. The workshop was organised by the Ethics Crossover Group in line with the aims and the scope of the ‘IMPROVE’ COST Action, to address the ethical dimension of research and experiments on laboratory animals.

Methodological choices in animal experimentation are influenced by a variety of factors. The analysis of the relative weight of such factors on the practice of animal experimentation can offer a better idea of the influences characterizing the work of researchers today. To this aim, we conducted structured interviews and sent out questionnaires to researchers using animal models. The results showed that the main factor influencing the researchers’ work with animals was the appropriateness of the chosen animal model to respond to the question addressed. Ethical issues came as the next important factor, mostly based on considerations regarding animal suffering. The general public opinion appeared to be of little significance, indicating that a gap still exists between animal researchers and society. This paper shows animal experimentation is influenced by both external (e.g., adherence to scientific objectivity) and internal factors (e.g., ethical concerns), providing a varied profile of the contemporary animal researcher.