Animal experiment statistics

In 2022, there were 2.7 million completed procedures involving living animals in Great Britain. These were regulated procedures, meaning they involved animals for an experimental or other scientific purpose or for breeding genetically-altered (GA) animals.

This was the lowest annual number since 2002 and was a reduction of 10% on the previous year and a reduction of nearly 20% on the number in 2019, before the pandemic and the UK’s exit from the EU.

The law on animal testing

The use of protected animals in any experimental or other scientific procedure which may cause pain, suffering, distress or lasting harm to the animal is regulated by The Animals (Scientific Procedures) Act0F 1986 (ASPA). Protected animals in the Act are any living vertebrate other than humans and any living cephalopod (marine animals such as squid).

Procedures on animals are falling in number

Pandemic aside, the annual number of procedures has been falling steadily since 2015, a year in which 4.1 million procedures on animals were carried out. The number in 2022 was 33% or around a third lower than this.

Numbers peaked in the 1970s, at around 5.6 million per year, before falling to around 2.7 million per year in the 1990s and early 2000s. The way in which procedures were recorded changed in 1987, which means figures before and after this date are not directly equivalent.

Reasons for experiments and animals commonly used

Around four in ten recorded procedures involve the creation or breeding of genetically altered (GA) animals. These procedures are almost all rated ‘sub-threshold’ or ‘mild’ in terms of severity), meaning the harm and/or discomfort they cause. The severity rating of a procedure is determined according to criteria set out in ASPA.

Most experimental procedures cause some degree of harm (ranked ‘mild’, ‘moderate’, or ‘severe’). In 4% of procedures carried out in 2022 the animal did not recover.

Four fifths of procedures in 2022 involved rodents, and two thirds of all procedures involved mice. Since 2007, fish have been the second most common animal used; before this it was rats.

In 2022, just over half (53%) of experimental procedures were undertaken for basic research, 24% for translational/applied research, 21% for regulatory uses, and a small number for other purposes.

The statistics in this briefing are for Great Britain, unless specified otherwise. They are mainly taken from the Home Office’s Statistics of scientific procedures on living animals.

Statistics for Northern Ireland are published separately by the Northern Ireland Department of Health.