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• 99% of procedures carried out in mice, fish, rats, and birds
• 82% of procedures caused pain equivalent to, or less than, an injection
• 69 research institutions and funders have proactively shared their 2025 animal research statistics

Understanding Animal Research (UAR) has published a of the ten organisations, which includes the University of Manchester,  that carried out the highest number of animal procedures 鈥� those used in medical, veterinary, and scientific research 鈥� in Great Britain in 2025. These statistics are freely available on the organisations鈥� websites as part of their ongoing commitment to transparency and openness around the use of animals in research. 

This list coincides with the publication of the Home Office鈥檚 on the statistics of scientific procedures on living animals in Great Britain in 2025. 

The ten listed organisations were responsible for 1,347,667 procedures, 53% (more than half) of the 2,537,507 procedures carried out on animals for scientific research in Great Britain in 2025*. Of these 1,347,667 procedures, more than 99% were carried out on mice, fish, rats, and birds and 82% were classified as causing pain equivalent to, or less than, an injection. 

The ten organisations are listed below alongside the total number of procedures they carried out in 2025. Each organisation鈥檚 name links to its animal research webpage, which includes more detailed statistics. Case studies explaining how animal research has been used in recent medical research are also provided in the Notes to Editors section. This is the eleventh consecutive year that organisations have come together to publicise their collective statistics and examples of their research.

Sixty-nine organisations have proactively published their 2025 animal research statistics

69 organisations in the UK that have publicly shared their 2025 animal research statistics. This includes organisations that carry out or fund animal research.

All organisations are committed to the ethical framework called the 鈥�3Rs鈥� of replacement, reduction and refinement. This means avoiding or replacing the use of animals where possible, minimising the number of animals used per experiment and optimising the experience of the animals to improve animal welfare. However, as institutions expand and conduct more research, the total number of animals used can rise even if fewer animals are used per study. 

All organisations listed are signatories to the , which commits them to being more open about the use of animals in scientific, medical and veterinary research in the UK. More than 130 organisations have signed the Concordat, including UK universities, medical research charities, research funders, learned societies and commercial research organisations.

Hannah Hobson, Head of Communications and Engagement at Understanding Animal Research, said: 鈥淎nimal research remains a small but vital part of the quest for new medicines, vaccines and treatments for humans and animals. Alternative methods are increasingly being phased in but, until we have sufficient reliable alternatives available, it is important that organisations that use animals in research maintain the public鈥檚 trust in them. By providing this level of information about the numbers of animals used, and the experience of those animals, as well as details of the medical breakthroughs that derive from this research, these Concordat on Openness signatories are helping the public to make up their own minds about how they feel about the use of animals in scientific research in Great Britain.鈥�

Dr Maria Kamper, Strategic Director of the Biological Services Facility at The University of Manchester, said: 鈥淪cientific research involving animals remains a cornerstone of our ability to understand complex diseases and develop life-saving medical breakthroughs. At The University of Manchester, we recognize that the privilege of conducting this research carries a profound responsibility 鈥� not only to the animals in our care but to the public we serve. Our commitment to the Concordat on Openness is reflected in our award-winning digital platforms, where we share the reality of our work through virtual tours, detailed case studies, and transparent data. However, transparency is only possible because of our foundational 'culture of care鈥�. By prioritizing exceptional animal husbandry, staff wellbeing, and ethical accountability, we ensure that our scientific excellence is always matched by our integrity. As we share our latest statistics, we remain dedicated to a sustainable research environment where open communication and world-class welfare standards go hand-in-hand to benefit society as a whole.鈥�

Case study: University of Manchester Why older mice have smaller offspring 鈥� and how sex may play a role

A study by University of Manchester scientists has revealed some of the mechanisms which may explain why older mice are more likely to give birth to offspring that have not grown to their full potential in the womb.

The study in older animals showed that the placentas of male but not female offspring had increased cell damage from a biological state called oxidative stress.

Oxidative stress occurs when harmful molecules called free radicals build up faster than the body can clear them.

It is associated with a range of pregnancy complications including fetal growth restriction and preeclampsia, both of which increase the risk of stillbirth.

The study demonstrated reduced weight in both female and male fetuses in older mice, but the placental alterations were sex-specific.

The scientists are conducting further studies in mice to confirm these findings and also carrying out a parallel study to see if similar sex differentiated mechanisms exist in human placentas from mothers of advanced maternal age (AMA), defined as age 35 and over.

The study, published in the journal Reproduction also discovered placental mitochondria 鈥� the biological batteries that power cells 鈥� were working at a reduced rate in the placentas of both male and female pups but that there were more of them.

Mitochondria are a major source of free radicals. Reducing their rate of activity at the same time as increasing their numbers is a way they adapt to prevent further oxidative stress while maintaining the supply of energy needed for cells to work properly.

This could mean that the adaptation in placentas from females was more successful than in placentas from males because oxidative stress was not increased in placentas from females of older mice.