Animal experimentation in Spain presents a troubling paradox: while the total number of animals used in research and education fell to 887,241 in 2024 — a 22.5% decrease compared to the previous year — the severity of the procedures they are subjected to has increased considerably. Procedures classified as “mild” dropped from 66% to 50%, while “moderate” tests jumped from 25% to 40%, and those considered “severe” rose from 5.8% to 7.8%, according to the annual report by the Ministry of Agriculture, Fisheries and Food (MAPA).
This trend is particularly concerning because it reveals that, although the absolute number of animals is decreasing, those who continue to be used are experiencing greater physical and psychological harm. “This is because in 2023 there was a spike in the use of fish, which has dropped sharply because that peak in experimentation in fish farms has ended,” explains Aïda Gascón, director of AnimaNaturalis in Spain. The activist notes that the statistical reduction does not necessarily reflect ethical progress, but rather the completion of specific projects that had inflated the figures.
The numbers behind the suffering
Mammals continue to be the most widely used group in Spanish research, with mice topping the list at 442,074 uses in 2024, representing nearly half of the total. They are followed by poultry with 141,000 uses and various species of fish. Basic research — especially in oncology (25% of uses) and the nervous system (23%) — accounts for most of these experiments.
The MAPA report also reveals that in 2024 the downward trend in non-recovery procedures was interrupted — that is, those in which the animal dies as part of the experiment. These uses increased by approximately 18%, although the ministry notes that the figures are similar to those of 2022 and represent 2.5% of the total.
One of the most revealing aspects of the official report is the explanation behind the apparent reduction. The drop of 211,629 animals used between 2023 and 2024 is explained almost entirely by the collapse in the use of sea bass, which fell from 337,536 to just 33,558 uses. This 90% reduction does not reflect systematic ethical progress, but simply the completion of a specific project in fish farms that had generated a temporary spike in 2023.
“When the number of uses of a species or for a particular purpose is small, variations that may seem very significant in relative terms often simply reflect the development or completion of specific projects,” explains the MAPA report itself. This reality underscores the need to analyze statistics with a critical perspective, avoiding unfounded optimistic interpretations.
In fact, if we exclude the variation in sea bass, the use of mammals increased by 6.52% in 2024. Mice, the most widely used species, saw a 13% increase compared to the previous year. Poultry experienced a 34% increase, and cephalopods — organisms with high neurological complexity — saw their use triple. Reptiles registered an increase of 313%, albeit from low baseline figures.
These data show that, far from a sustained downward trend, animal experimentation in Spain fluctuates significantly depending on the projects active at any given time, without there yet being a clear national strategy for its progressive reduction through validated alternatives.
In addition, the report details that 31% of the animals used in 2024 were genetically modified, 88.7% of them mice. The creation and maintenance of these genetic lines account for 5.05% of total uses, an area in which Spain is developing models for complex human diseases such as Parkinson’s, Friedreich’s ataxia, or Alzheimer’s. Although these projects pursue legitimate medical advances, they raise ethical dilemmas about the extent to which it is acceptable to create animals destined to suffer severe diseases throughout their lives.
“It is a very opaque sector, the most opaque of all. It’s impossible to get inside unless you go undercover, as happened with Vivotecnia,” denounces Gascón, recalling the 2021 scandal when an investigation by the NGO Cruelty Free International exposed systematic abuse practices at the Madrid-based laboratory. However, the director of AnimaNaturalis acknowledges the complexity of the debate: “We cannot oppose research in oncology or in diseases of the endocrine, nervous system, etc. If there is no alternative, we have no choice but to accept it,” adds Gascón, while insisting on the urgent need to promote and fund alternative methods.
The European legal framework and validated alternatives
The European Union has been a pioneer in establishing a regulatory framework that drives the reduction and replacement of animal experimentation. The 3Rs principle (Replacement, Reduction and Refinement), set out in European Directive 2010/63/EU and transposed into Spanish law through Royal Decree 53/2013, obliges researchers to seek alternatives whenever possible.
One of the most significant advances has been the total ban on animal testing for cosmetic products since 2013, a measure that has driven the development of validated alternative methods. The REACH Regulation (Registration, Evaluation, Authorisation and Restriction of Chemicals) also actively promotes the use of non-animal methods for chemical safety assessment.
The European Centre for the Validation of Alternative Methods (ECVAM), part of the Joint Research Centre of the European Commission, has officially certified more than 30 alternative methods that can replace or significantly reduce the use of animals in different areas of research. These include tests for skin and eye irritation, acute toxicity, skin sensitisation and genotoxicity.
In addition, the European Commission is actively working on a roadmap to phase out animal testing for chemical safety assessments, as announced in 2024. This initiative complements similar efforts in the United States, where the Food and Drug Administration (FDA) updated its regulations in 2023 to allow certain medicines to progress to clinical trials without prior testing in animal models, provided there is robust evidence from validated alternative platforms.
Revolutionary technologies already available
The scientific landscape is undergoing a quiet but profound revolution. “Organs-on-chips” — miniaturised versions of human organs grown in plastic capsules — are already being used by regulatory bodies such as the FDA to evaluate drugs and vaccines. During the COVID-19 pandemic, human lung chips were used to assess vaccine safety, demonstrating that these technologies are not a future promise but a present reality.
Researchers at the University of California, Riverside have succeeded in creating fully synthetic functional brain tissue, with no components of animal origin. This structure, described in the journal Advanced Functional Materials, allows stem cells to organise into operational neural networks that can be used to study diseases such as Alzheimer’s or brain injuries, and to test drugs with greater precision than traditional animal models.
Organoids — three-dimensional structures that replicate human organs — are also transforming research. They can be personalised using cells from the patient themselves, making it possible to model specific diseases and test individualised treatments without resorting to animals. Some laboratories are already working on connecting several of these systems to create a “body-on-a-chip” that mimics complete human physiological interactions.
Artificial intelligence is accelerating this shift. Machine learning algorithms can now design entirely new drugs, predict their toxicity and efficacy, and even create “digital twins” of human organs to simulate treatments before testing them on real people. The Wyss Institute at Harvard and DARPA (the research agency of the U.S. Department of Defense) are leading projects on interconnected multi-organ platforms that recreate human physiological responses with unprecedented accuracy.
The United Kingdom sets the pace
In a historic decision, the UK government announced in 2024 an ambitious plan to gradually eliminate animal experimentation. Tests for potential skin irritants in animals will be suspended by the end of 2025, and by 2027 tests of Botox potency in mice are expected to end. Drug testing on dogs and non-human primates will be significantly reduced by 2030.
This government strategy acknowledges that, although regulatory bodies such as the FDA, the European Medicines Agency (EMA) and the World Health Organization (WHO) still require certain animal tests, technological advances in recent years have been so spectacular that a future without animal experimentation is no longer a utopia, but an achievable goal.
Transparency as the first step
In Spain, the Confederation of Scientific Societies of Spain (COSCE) has maintained a transparency agreement since 2016, to which 170 institutions have signed on — the highest number worldwide. One hundred percent of these institutions now have a public statement on their websites regarding the use of animals in research, a radical change compared to 2014, when no institution provided public information on the subject.
Lluís Montoliu, a researcher at the CNB-CSIC and CIBERER-ISCIII, and author of the ministry’s report, argues that “we only use animals in research when there are no alternative models available, and only experiments that have been exhaustively justified and documented are carried out, reviewed by up to three successive committees and authorised by the competent authority”.
However, Gascón points out that real transparency goes beyond institutional statements: “Those protocols and oversight need to be improved,” insists the director of AnimaNaturalis, referring to cases such as Vivotecnia, where official inspections failed for years to detect abusive practices that were ultimately revealed through an undercover investigation.
A commitment to the future
Biomedical research has relied on animal models for centuries, contributing to fundamental discoveries such as vaccines against smallpox and polio, or the development of insulin. No one questions the historical importance of these advances. However, more than 90% of drugs that pass animal testing fail in human clinical trials due to fundamental differences between species, raising serious doubts about the efficiency of the current model.
Technological alternatives are not only ethically superior — by eliminating animal suffering — but also offer models that are more precise, more relevant to humans, reproducible and economically viable in the long term. Official European validation of these methods guarantees their scientific reliability, while their progressive incorporation into legislation demonstrates that change is possible.
“We advocate eradicating the use of animals for scientific, experimental and educational purposes and replacing them with alternatives such as computer-based methods or cell cultures, among others,” concludes Gascón. The director of AnimaNaturalis acknowledges that the transition will not be immediate, but insists that the European Union is actively exploring these avenues, with specific funding for the development and validation of new alternative methods.
Your choice matters
As consumers and citizens, we can all help accelerate this change. By choosing products — from cosmetics to cleaning products — that are explicitly certified as free from animal testing, we send a clear signal to industry about our ethical values. Labels such as Cruelty Free or the leaping bunny logo guarantee that no animal has suffered in the production of these items.
Moreover, sharing information like that contained in this article helps create a more informed and demanding society. The better informed the public is about available alternatives and technological advances, the greater the social pressure on governments and institutions to accelerate the transition toward research methods without animal suffering.
The future of science does not have to include the pain of millions of sentient beings. The tools already exist, legislation is advancing, and technology is ready. All that is needed is the collective will to make the 21st century the era in which humanity finally left animal experimentation behind — not by renouncing scientific progress, but precisely by achieving a superior one: more ethical, more accurate and more humane.
