Numbers and types of animals used in research

Genetically modified mice.


Every year, we record the number of regulated procedures conducted on animals and report these to the Home Office.

A 'procedure' refers to anything done to an animal that may affect its wellbeing. This includes using an animal in a research project, and creating or breeding a genetically altered animal. A procedure may involve one intervention, such as a single injection, or could refer to sequence of events, such as inducing, treating and analysing a tumour.

We publish the numbers of procedures conducted at the Crick by species, type and severity. The data is presented in interactive charts below, with numbers and percentages available when you hover over each segment. The numbers are also available in tables.


The charts below show how many procedures involving each species were conducted at the Crick in 2020.


Mice: Used in a wide range of research projects, often genetically altered to explore the roles of different genes and pathways, or to test potential treatments.

Fish: Used to study genes, signalling pathways and other factors involved in development.

Frogs: Used in developmental biology, for example to see which processes are the same in amphibians and mammals.

Ferrets: Used in flu research and vaccine development, as they catch human influenza viruses and respond similarly to humans.

Opossums: Used to study genes, helping to answer questions about fertility and developmental disorders.

Other species

Type of procedure 

Procedure types

Breeding and maintenance: breeding an existing type of genetically-modified animal.

Experimental use: procedures done as part of a research project. Each procedure could be one intervention, such as a single injection, or a sequence of events, such as inducing, treating and analysing a tumour.

Creation of new line: creating a new type of genetically-modified animal.


Severity levels

Sub-threshold: the procedure has a negligible impact on the animal's wellbeing. For example, the birth of a healthy genetically modified mouse.

Non-recovery: the procedure is done under general anaesthesia and the animal is humanely killed without regaining consciousness.

Mild: the procedure only causes minor, short-term pain or distress with no lasting impact. For example, a healthy mouse undergoes blood testing.

Moderate: the procedure may cause pain, distress or discomfort and a noticeable disturbance to the animal's natural state, but they are able to move, eat and drink relatively normally. For example, a mouse is given cancer, develops tumours, then undergoes imaging and treatment similar to a human patient.

Severe: the procedure has a major impact on the animals' health and wellbeing so that they don’t live or behave normally. They may experience a significant level of pain, distress or discomfort. For example, a ferret is infected with flu and experiences serious symptoms including fever, lethargy and weight loss.


Previous years

Data for previous years is given below, starting in 2017 when animal research was centralised into our purpose-built facility at the Crick.

Previous years

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Data tables