Numbers and types of animals used in research

Species

These charts show how many procedures involving each species were conducted at the Crick in 2024.

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.

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. This could be by crossing two existing lines to answer a new questions, or by designing a new modification. 

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. 

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. At the Crick, we study mice who have cancer and some may experience moderate discomfort such as losing weight or are less active. In doing this, researchers can probe into the biology of the tumour and identify potential targets for new drugs.

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. At the Crick, we study mice infected with viruses or bacteria. A small proportion of these mice undergo an entire infection that involves periods where the animals rapidly lose weight, have decreased movement and laboured breathing. The mice typically recover within 5–7 days. These studies help researchers to gain invaluable knowledge about the immune system, which helps to develop therapies that could alleviate symptoms or prevent infections developing.

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.