The use of animals in research is regulated by the Animals (Scientific Procedures) Act 1986. ( This applies to all vertebrate animals and cephalopods (e.g. octopus and squid).

A regulated procedure under the Act is any procedure applied to a protected animal for a qualifying purpose which may have the effect of causing the animal a level of pain, suffering, distress or lasting harm equivalent to, or higher than that caused by the insertion of a hypodermic needle in line with good veterinary practice. This is known as the threshold.

In addition, any genetically altered animal that is bred or used under the Act needs to be reported. Genetically altered (GA) animals may be natural mutants or genetically engineered (also known as genetically modified).

In order to undertake experiments under A(SP)A the individual doing the work must be trained and have been granted a Personal Licence by the Secretary of State. They must work under an approved programme of work, which is the Project Licence and the place where the work is done must have been designated by the Secretary of State as a scientific procedure establishment (though the granting of an Establishment Licence certificate). Licensing is operated by the Animals Scientific Regulation Unit (ASRU) which operates on behalf of the Secretary of State for the Home Office.  

As a condition of being given a licence to conduct work under the Act, an annual report is required to be submitted to the Home Office for each project licence held, detailing the number and type of animals used in the previous year and the actual degree of pain, suffering, distress or lasting harm experienced by each animal (known as severity categories).  These reports are known as the Annual Returns of Procedures and are submitted each January. 

There are 5 severity categories:

Sub-threshold severity- for example a GA animal with no harm caused by the genetic alteration

Mild procedures – Transient and minor pain, for example an injection or the withdrawal of a blood sample.

Moderate procedures – moderate severity is greater than transient pain - for example surgery under anaesthesia (loss of consciousness) with analgesia (painkillers post-surgery).

Severe procedures – something that a normal human would not wish to endure (for example a heart attack).   Note that animals undergoing procedures that are found dead are classified as severe unless there is clear evidence that would support a lower category.

Non-recovery – where an animal has been put under general anaesthesia and does not wake up again so any suffering of the animal may endure is prevented once it is fully anaesthetised.

How many animals were used by the RVC in 2023?

 In 2023, the RVC used 5948 animals in research carried out under a Home Office project licence. The vast majority of these were mice, zebrafish and domestic fowl.  The latter species is used for applied research, the aim of which is to develop new treatments that improve the welfare of commercially reared chickens globally.

The figures below, show the numbers of scientific procedures that were carried out at the RVC on animals.  These figures were declared to the Home Office as part of the 2023 annual return of procedures. 

The numbers of animals that had procedures carried out on them were:

Alpacas 1
Cattle 1
Dogs 108*
Domestic fowl 607
Mice 2514
Pigs 141
Rats 130
Sheep 27
Zebrafinch 18
Zebrafish 2401
Total 5948

*There has been an increase in the numbers of client owned dogs used compared to 2022.  The procedures were blood samples taken from the dogs with their owner permission and prior information that their pet would be temporarily enrolled under A(SP)A.    Further information about why we use client-owned animals is available below.

Numbers of procedures carried out: 

Alpaca 1
Cattle 1
Dogs 108
Domestic fowl 2019
Mice 2497
Pigs 141
Rats 130
Sheep 27
Zebrafinch 18
Zebrafish 2357
Total 7299

Number of animals that were killed following procedures carried out were: 

Dogs 20
Domestic fowl 607
Mice 2514
Pigs 141
Rats 130
Sheep 27
Zebrafinch 18
Zebrafish 769
Total 4226

The Severity classifications of the  procedures that were carried out:

Mild Moderate Non-Recovery Severe Sub-threshold Total
4399 867 130 35 1868 7299
60.3% 11.9% 1.8% 0.5% 25.6%  

The following numbers of animals were either rehomed or returned to their owners:

Animals rehomed
  Rehomed Returned to owners *
Dogs 54 69
Guinea Pigs** 5  
Hamsters ** 4  
Rats** 3  

* these were client-owned animals where their owners gave permission for their animals to be used in studies conducted under A(SP)A (see text for further information).

** These were teaching animals

At the RVC we run studies under A(SP)A that involve client-owned animals, who are veterinary patients.  These studies involve procedures of recognised veterinary practice that cannot be undertaken under the Veterinary Surgeons Act (such as taking additional blood samples), as these tests are for research purposes, rather than for the direct clinical benefit of the animal involved in the study.  The client-owners all gave informed consent for their animals to be involved in these studies and they were returned to their care at the end of each procedure.  Involvement in these studies was voluntary and the owners could withdraw their animals at any time. A decision to do so, or a decision not to be involved in the study, did not influence the care the animal received in any way.

We also have a dog colony in which we are studying and looking after dogs that have Duchenne Muscular Dystrophy.  As part of the management of this colony, we rehome puppies that are unaffected by this disease.  For more information on these types of studies and the animals involved see Research using Client-owned Animals. Also see Use of Animals in Research - Case Studies for a series of short articles explaining how and why we use animals in research at the RVC.

The proportion of our funded research that relates to animal work:

As a measure of the proportion of our research that involves experimental animals, the amount of external grant funding used to cover the costs of purchasing and keeping the animals has been calculated as a percentage of the total non-pay spend from external grants. This is 20.5%.  

BSU charges to research grants - total           £639.511
Total non-pay cost to research grants       £3,148,000
%               20.5%


For details of animals used in previous years please see:

2022 figures

2021 figures

2020 figures

2019 figures  

2018 figures

2017 figures

Top of page