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.



These charts show how many procedures involving each species were conducted at the Crick in 2022.

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.

Other species

Zebrafish: Used to study genes, signalling pathways and other factors involved in development.
Guppies: used for understanding how new organs are created by studying the placenta
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.


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, a mouse was given its normal diet with the addition of a compound present in broccoli to see if the compound improves its gut health. The addition of the compound didn’t affect the amount of food, and after three months, the mouse was humanely killed, and the gut was analysed. 
Non-recovery: the procedure is done under general anaesthesia and the animal is humanely killed without regaining consciousness. For example, a mouse is put under general anaesthesia and electrodes are inserted into its brain in order to record its brain signals while it is unconscious. The mouse is humanely killed while still under anaesthesia. 
Mild: the procedure only causes minor, short-term pain or distress with no lasting impact. For example, a mouse is given a low-protein diet after weaning, and has blood collected weekly for analysis through a prick in its tail vein. After four weeks, the mouse is humanely killed and the tissue is used to study the effect of a low-protein diet on organ development.
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 genetically altered zebrafish is used for egg collection. It develops a curved spine that compromises its normal movements, and the animal is humanely killed when the curvature becomes apparent. 
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 mouse has its thymus surgically removed in preparation for more experiments. The mouse recovers completely from the anaesthesia but the following morning it is reluctant to move and not eating or drinking. The mouse is humanely killed.

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

dummy break

Data tables