Animal Use Statistics

Black mouse peering over the top of container

The Babraham Institute animal research numbers and uses

The research carried out at the Babraham Institute seeks to advance our understanding of the fundamental processes in our cells, and how cells and systems function differently as we age. Our researchers work to uncover the biological ‘nuts and bolts’ of how we function and this knowledge is subsequently used to identify novel targets for the development of therapies and diagnostics applicable to autoimmune diseases, cancers, diseases of neurological decline such as Alzheimer’s, to reproductive disorders and many others. In some cases, it is necessary to study or utilise biological responses that cannot be reproduced in tissue culture or investigated using alternative systems. This means that where there are no other alternatives, research involving mice and rats takes place at the Institute in line with the animal research policy.

The UK Home Office records numbers of regulated animal research procedures carried out on protected species by UK research institutions to produce a comprehensive annual statistical report. As part of the Babraham Institute’s commitment to openness around animal research the statistics below show the number of procedures undertaken to support the work of our researchers across the Institute’s three research programmes in 2022, 2021 and 2020. These statistics do not represent the animal research statistics for the wider Babraham Research Campus.

Animals used in research

Before research using live animals can begin, project proposals are subject to a thorough approval process. At the Babraham Institute, mice are the only protected species used in research. The numbers of procedures undertaken for 2020 to 2023 are reported below. A regulated procedure is anything done to a protected animal that may cause a level of pain, suffering, distress or lasting harm equivalent to, or higher than, that caused by inserting a hypodermic needle according to good veterinary practice. This includes breeding genetically modified animals.

The table below shows the number of procedures carried out each year.

Type of animal 2020 2021 2022 2023


48,599 40,750 39,157 33,364

Types of procedure and severity ratings

Animal welfare is a priority during procedures, in line with the refinement goal of the 3Rs, with the minimum amount of discomfort, harm and distress being caused while meeting the study aims. Before experiments take place, researchers must describe the expected suffering animals may experience. Levels of severity are described by the Home Office to describe the pain or distress to an animal during a regulated procedure, based upon the greatest degree of pain, suffering, distress or lasting harm allowed to be experienced by any animal within that protocol after applying all appropriate refinement techniques.

After the completion of a series of regulated procedures for a particular research purpose, the actual severity of the procedures must be rated using careful monitoring and assessment of the animals and this information is included in data returned to the Home Office for work performed under project licences.

Sub threshold

Procedures are classified as sub-threshold when they do not cause suffering above the threshold for regulation. This number can include procedures for which a higher severity rating was anticipated but which did not occur.

Examples include:

  • Breeding of genetically altered animals without a harmful effect
  • Animal handling procedures


Procedures that cause short-term mild pain, suffering or distress, as well as procedures with no significant impairment of the wellbeing or general condition of the animals are classified as mild. Mild procedures generally have no lasting impact on animals; once each step within a procedure has been completed the animal should return to normality, or close to it, almost immediately.

Examples include:

  • Pain caused by a standard injection, such as taking a blood sample
  • Induced ovulation in female mice, used to increase the number of ooctyes for the production of genetically engineered mice


Procedures where animals are likely to experience short-term moderate pain, suffering or distress or long-lasting mild pain, suffering or distress as well as procedures that are likely to cause moderate impairment of the wellbeing or general condition of the animals are classified as moderate. Moderate procedures cause a significant and easily detectable disturbance of an animal’s normal state. The disturbance is enough for an animal to show discomfort, for example hunching posture or fur bristling (piloerection), abnormal behaviours, significant weight loss or other indicators of poor welfare, but does not prevent normal feeding and drinking or other normal activities other than for short periods or to a limited extent for longer periods.

Examples include:

  • Introducing pathogens to stimulate short to medium term illness
  • Vasectomy in male mice to create sterile males used in mating to create pseudo pregnant females as embryo recipients.


Procedures causing animals to experience severe pain, suffering or distress or long-lasting moderate pain, suffering or distress, as well as procedures that are likely to cause severe impairment of the wellbeing or general condition of the animals are classified as severe. Severe procedures cause a major departure from the animal’s usual state of health and wellbeing, for example where assistance with normal activities such as feeding and drinking are required or where significant deficits in behaviours/activities persist.

Examples include:

  • Research involving the induction of tumours, or with mice strains that spontaneously develop tumours, that are expected to cause progressive lethal disease associated with long-lasting moderate pain, distress or suffering.
  • Where brain inflammation is triggered by immunisation of mice with myelin derived antigens


An entire procedure performed under general anaesthetic where the animal does not recover consciousness.


Breakdown of procedures that took place as part of research at the Babraham Institute

Severity Procedures 2020 % of total in 2020 Procedures 2021 % of total in 2021 Procedures in 2022 % of total in 2022 Procedures in 2023 % of total in 2023
Sub-threshold 7,613 >15.7% 4,008 9.8% 4,069 10.4% 25,585 76.7%
Mild 40,223 82.8% 36,093 88.6% 34,651 88.5% 7,349 22%
Moderate 664 1.4% 514 >1.3% 389 1% 375 1.1%
Severe 99 0.2% 135 0.3% 48 0.1% 55 0.2%
Non-recovery None 0% None 0% None 0% None 0%

% of procedures in 2023 at each severity level shown in a pie chart: Mild 22.0%, Moderate 1.1%, Severe 0.2%, Sub-threshold 76.7%, Non-recovery 0%

Reducing harms

Whenever an adverse event is possible, and with procedures that might result in an immediate impact on wellbeing, animals are always carefully monitored so that action can be quickly taken to reduce suffering either through treatment or through humane death.

After surgery, mice receive post-operative care until they are well enough to return to their usual boxes. Mice are naturally social animals, and therefore housed in small groups. Under day-to-day care, social housing of animals can cause fighting, particularly between male mice, so animal technicians are always on the lookout for signs of aggression and injury with procedures in place to both reduce animal stress and aggression, and create non-stressful social groups. Where mice need to be individually housed, they are provided with increased enrichment to provide additional stimulation.  

For more information on how we work to ensure the highest standards of animal welfare, see the Animal Welfare and Care page.