At the same time, besides human studies (mainly pharmaceutical ones), animal research is one of the most regulated areas of science, with strict ethical oversight and a growing investment in alternatives. Yet despite this structure, there seems to be a persistent gap between what happens within research institutions and what society understands about them.

The conversation exists, but often in fragments, shaped by extreme positions, isolated images, or just silence. If science is financed largely by public institutions and, above that, is meant to be a public good, then this is a topic that deserves a more open and informed discussion.

From Historical Practice to Modern Regulation

For centuries, animals have been used for biomedical research to understand anatomy, physiology, and disease. What has changed significantly, since the beginning, is how this use is framed, regulated, and justified. A major turning point came in 1959 with the publication of The Principles of Humane Experimental Technique, which introduced the Three Rs: Replacement, Reduction, and Refinement. These principles changed how scientists approached animal research, in an attempt to improve both ethics and science, since poor animal welfare was shown to be associated with unreliable data, meaning that ethical considerations and scientific quality were interconnected.

Today, within the European Union, countries operate under Directive 2010/63/EU, one of the most comprehensive regulatory documents worldwide. It recognises animals as sentient beings and requires that all projects undergo harm–benefit analysis before approval. Researchers must justify why animals are necessary, demonstrate that no viable alternatives exist, and ensure that suffering is minimised.

Portugal follows this directive through Decree-Law 113/2013. In practice, this means that any research involving animals must pass through multiple layers of oversight. Researchers require formal training and accreditation, institutions must have Animal Welfare Bodies responsible for evaluating projects and monitoring compliance and facilities are inspected regularly, sometimes without prior notice. Importantly, this system is explicitly designed to reduce and ultimately replace animal use.

What Happens Inside an Animal Facility, and Why It Matters

For many people, the idea of an animal facility is abstract, often shaped more by sci-fi films than by direct knowledge. In reality, these environments are highly controlled and standardised.

Animals are housed under carefully regulated conditions, including temperature, light cycles, and environmental enrichment. Their health is continuously monitored by trained personnel and veterinarians. Every procedure must be approved in advance, categorised by expected severity, and later reported based on the actual impact on the animal. This does not remove the ethical tension inherent to animal experimentation. It does, however, show that the actual system is built around acknowledging that tension.

At the same time, the scientific justification for using animals remains tied to their biological complexity. Living organisms allow researchers to study interactions that cannot yet be fully replicated in vitro or in silico. Immune responses, hormonal regulation, and behaviour are examples of systems where multiple layers of biology interact in ways that are still difficult to model.

However, there are limitations: animal models do not perfectly replicate human biology, and many findings fail to translate into effective treatments, contributing to what is often described as a reproducibility or translation problem in biomedical research. In parallel, alternative approaches are expanding rapidly. Nowadays, before moving to animals or for a specific mechanistic hypothesis (for example, the effect of a compound in a specific cell), researchers resort to cell cultures, organoids (organ-like cell structures grown in a lab), computational models, and micro-physiological systems, which are becoming more sophisticated and perfected. In Europe, for example, animal testing for cosmetics has already been banned. The current landscape is therefore in transition, where traditional models coexist with emerging technologies that aim to replace them.

Transparency, lack of it and its influence on public perception

Given the level of regulation and the scientific importance of the topic, one might expect animal experimentation to be widely discussed. And in fact, this happens within the scientific community and to an extent in the public sphere (mainly by non-profit organisations). However, there seems to be a lack of an open channel between both.

Part of it lies in the misconception about how animals are treated today. Communicating about animal research involves exposing a not-so-agreed-upon ethical dilemma, requires explaining complex procedures, ethical trade-offs, and scientific uncertainties, and it also involves the risk of misinterpretation, particularly when images or videos are taken out of context. Importantly, we have to acknowledge the past of mistreatment and some documented cases of misconduct which had a lasting impact on public perception, and that may explain why institutional organisms often remain cautious.

Recent data from the Portuguese Transparency Agreement on Animal Research suggested that internal resistance and lack of resources are still identified as barriers to greater transparency. Despite that, most participating institutions reported proactive efforts to communicate with the public. Many use social media, organise events, and provide opportunities for visits. Some have started to share images and videos of their facilities and animals. Although only a small number of institutions publish accessible summaries of their research or detailed statistics on animal use.

This creates an interesting paradox. On the one hand, there is a growing willingness among scientists to communicate. On the other, there are still structural and cultural factors that limit how far this communication goes. The result is a fragmented picture, where information exists but is not always easily accessible or consistently shared.

What is the future like?

The future of animal experimentation will gradually change. Every day, new human-relevant models are being developed, experimental design, and transparency are being taken more seriously than ever in funding applications, research article submission and ethical committees. The ultimate goal is that, at the same time, we reduce animal use; we also ensure a smooth transition that still produces meaningful and reliable knowledge.

We cannot ignore that science depends on public trust and has the obligation to provide a better understanding of what it is doing. Despite the increase in the communication of animal use transparency, the scientific community needs to do more. Acknowledging its limitations and explaining its role may be as important as any technological development. It is evident that it could trigger a broader public discussion, but it is preferable that it happens based on information rather than assumptions.

In the end, the question may not even be whether animal experimentation should exist in its current form, but how long it will remain necessary. The answer will likely depend not only on scientific progress, but also on how willing we are to confront the topic publicly. Because if there is one thing that seems clear, it is that silence has not made the discussion easier nor changed policy and society perception for the better.