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Scientists comment on the annual statistics, published by the Home Office, on the use of animals in scientific procedures.
Prof Robin Lovell-Badge FRS FMedSci, Group Leader, Francis Crick Institute, said:
“Animal research is never undertaken lightly and is supported at many levels with all working to ensure the 3Rs are upheld and animals undergoing procedures are cared for in the best way possible. This includes well-trained animal technicians, facility managers and vets who all help scientists to design experiments, ensure the animals are maintained and worked on in the best conditions, and to spot and deal with any issues. While there is a push to switch to in vitro systems or in silico modelling, these do not yet permit studies where these cannot adequately replicate the in vivo situation. These include exploring mechanisms underlying the function of the brain or behaviour, immunology, physiology, endocrinology or reproduction where the connections between organs and whole animal responses are critical. Testing interventions to treat disorders affecting these systems also requires study in whole animals. It may be some time before we can find non-animal alternatives when the biology is complex, although we try, as evidenced by the rapidly expanding use of organoids and stem cell-based embryo models.”
Professor Sarah Bailey, academic co-chair of the UK Bioscience Sector Coalition (UKBSC), and Professor of Neuropharmacology at the University of Bath, said:
“Medical progress and the discovery of new medicines for both people and animals depends on the careful and ethical use of animals in research.
“The annual statistics on scientific procedures shows the number of procedures involving animals has gone down.
“The number of procedures using animals in the UK is now about 77% of what it was in 2019, before COVID.
“The number of animals used in research depends on things like how much money is available for research, what kinds of research organizations are focusing on and developments with new non-animal methods that support or replace animal research.
“In the UK, animal research is funded by the government through research councils (UKRI), as well as by charities and private companies. Because of the current economic challenges – higher costs and tighter budgets – there has been a reduction in research overall, which may explain the lower number of procedures in 2024.
“As in past years, just over half of procedures are classified as “experimental procedures”. Most of these are basic research which means studying how living things work at fundamental level.
“Some procedures are required by law, such as testing new medicines for safety. Animals are also used in applied research – studies that aim to understand, prevent or treat diseases in humans and animals.
“The most common research areas using animals stay fairly similar each year. They focus on major health problems such as cancer, the immune system and infections, the brain and mental health disorders.
“The types of animals used in research also stay about the same each year. This year, the majority of procedures use mice (57%), fish (16%), rats (10%) and birds (8%).
“Each animal’s experience is judged by the “severity” of the procedure, meaning how much pain, suffering or distress it causes. Mild procedures cause short, minor discomfort and quick recovery. About half of all procedures fall into this category.
“If an animal has surgery, it does so the same way a human does – with general anaesthesia, pain relief before, during and after, and enhanced monitoring during recovery. This would be classified as a moderate severity procedure as it disturbs the animal’s state more seriously. These make up about one-third of all procedures.
“Every year, the Home Office reports any “techniques of special interest”. This includes checking if animals were used to test ingredients for household products or alcohol and tobacco products. In 2024, there were no such tests.
“A new addition this year is the forced swim test, which is now classed as a “technique of special interest”. In this test, an animal is placed in water, out of its depth with no means of escape.
“In 2023, the Animals in Science Committee said that the forced swim test can help study antidepressants and stress-related behaviour. For mice, it usually means a 6-minute swim in a cylinder of water, after which they are dried, warmed and returned to their cage.
“In 2024, there were 250 procedures involving mice in this test, all rated as either mild or moderate severity.
“Non-animal research methods are improving all the time and, alongside animal research, are important in advancing UK bioscience. However, animals are still needed when there are no alternatives. Understanding complex biological systems, studying disease over the lifespan, and testing how new medicines work in the body requires the use of animals.”
Dr Doug Brown FRSB, Chief Executive of the Royal Society of Biology, said:
“Animal research continues to play a critical role in biomedical research, advancing our understanding of complex biological systems and disease mechanisms. Scientific research involving the regulated use of animals has been instrumental in progress across areas such as gene and vaccine therapies, cancer screening and treatment, and continues to provide vital insights into the physiological and genetic mechanisms underlying metabolic diseases, and neurodegenerative disorders such as Alzheimer’s.
“Significant advances are being made to phase in non-animal alternatives, including organ-on-a-chip technologies, human cell-based approaches and the growing integration of computational and AI-based methods. These alternatives are used across an increasing number of applications, which hold promise to reduce our reliance on animal use within certain contexts.
“We welcome the Government’s decision to publish a strategy aimed at accelerating the development, validation and uptake of alternatives to animal use, expected later this year. We hope this will support the ongoing efforts and progress made by the life sciences community. However, we recognise that animal research will remain necessary for the foreseeable future to develop medical treatments for both humans and animals, and to safeguard human, animal, and environmental health.
“The UK life sciences community remains committed to achieving the scientific benefits of animal research while minimising harm. This commitment is upheld through adherence to the high standards of animal welfare and the application of the 3Rs principles: Replacement, Reduction, and Refinement.
“The UK has a highly robust regulatory framework ensuring that scientists and laboratory staff are qualified and competent before conducting procedures on animals. Every research project is individually assessed and licensed by the regulator, and reviewed by local ethical committees.
“The Royal Society of Biology supports the use of animals in research when no alternatives are available, and is committed to promoting openness and transparency in reporting the use of animals for scientific purposes”.
Chris Magee, Head of Policy and Media, Understanding Animal Research, said:
“Animals are used in research in the UK to help discover, develop and test new medicines for humans and animals. They are also used for conservation research and to protect our environment and the safety of our food. No animal is used if there’s an alternative, and no animals are used to test cosmetics, tobacco, alcohol or household products. The number of animals used each year can go up or down depending on various factors including investment in the UK biosciences.
“Overall numbers have been on a gradually decreasing trend since the mid-1970s and 2024’s drop is in line with that trend.
“The 2024 statistics seem much as in previous years. Just under half of procedures are breeding animals with particular genetic qualities and the rest are more traditional categories such as medical research. Procedures using mice, fish, rats and birds are the most common by far, making up 95% of the total. Experiments which result in severe suffering continue to be relatively rare at 2.25% of all procedures (3.27% of experimental procedures and 0.92% of breeding procedures).
“The number of dogs used decreased by about a third. There is currently no alternative to using dogs for some regulatory toxicology requirements, so it is unclear at this time whether this is due to work moving abroad, and outside of the special protections for dogs in research which are unique to our country, or whether fewer potential new medicines went through toxicology testing in 2024.
“The number of amphibians used in research tripled in 2023 and we see similar numbers persisting into 2024, although the focus of the research has shifted from translating findings into humans back towards basic research into how biology functions.
“We will always avoid animal use where we can, but these figures show that in a wide range of areas animal research remains the only proven way of saving and improving human and animal lives.”
Dr Vicky Robinson CBE, Chief Executive, NC3Rs, said:
“As always, the release of the annual statistics on animal procedures presents an interesting snapshot of animal use in Great Britain. The continuing downward trend in the number of procedures is influenced by a range of factors including the efforts of the scientific community to find alternative methods, changes in scientific trends and investment decisions on where research is placed. In recent times there has been a significant uptick in efforts to replace the use of animals globally with many governments and research organisations increasing their commitments to technologies that replace the use of animals. The UK has long been at the forefront of these efforts and it is essential given the scientific, economic and societal benefits that this position is maintained. We are looking forward to the forthcoming UK government plan on alternative methods and are excited about the role that the NC3Rs can play in supporting the delivery of this, given our expertise, networks and partnerships with key industry, academic and regulatory organisations.”
‘Statistics of scientific procedures on living animals, Great Britain: 2024’ was published by the Home Office on Thursday 23rd October 2025
https://www.gov.uk/government/statistics/scientific-procedures-on-living-animals-great-britain-2024
Declared interests
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