Project Licences (PPLs)

An introduction

The project licence is central to the operation of A(SP)A. A project licence is granted to an individual to manage a program of research (“experiments”) that involves regulated procedures on protected animals. As a personal licence holder (or “licensee”), you cannot conduct any procedures on animals unless a project licence has been granted, authorising those particular procedures, for a specified purpose. You must also have been given the approval of the holder of the project licence to work under the authority of their licence.


The rest of this article is restricted to members only. Learn more or

Project licences are usually granted for a period of five years, to the person in charge of the study (the Project Licence Holder). The project licence will include details of the applicant, and why they are an appropriate person to hold the licence. It will give the scientific background to the program of work and set out clearly the aims and objectives of the project. The benefits that will arise from the work, if successful, should be clearly stated. The objectives and the anticipated benefits should be attainable within the 5 year duration of the licence, and with the resources that are available.

The licence will explain why animals need to be used in the project, what alternatives have been considered and why they are not suitable (Replacement). It will also explain how the numbers of animals to be used has been estimated. This will usually show how the principles of good experimental design will be applied and may require evidence of Power calculations or other methods of ensuring appropriate numbers, ie neither too many nor too few animals, are used (Reduction).

Principles of good experimental design are summarised in the ARRIVE guidelines , Festing et al, 2016 and the NC3Rs experimental design toolkit .

The licence will also detail how the principles of Refinement have been applied. Refinement in this context means reducing to a minimum the pain, distress or lasting harms in the animals that it is still necessary to use (after applying replacement and reduction) in the project. This can encompass choice of the least harmful models, selection of the least sentient species, and adoption of measures to alleviate pain or distress (for example by use of analgesics after surgical procedures). It will also require a description of the humane endpoints that will be used, and justify why these endpoints are the earliest which allow the scientific objectives of the study to be achieved. Positive measures to refine studies can also be taken, such as provision of additional environmental enrichment. Housing social animals in isolation, or in cages smaller than those specified in the Home Office Code of Practice are not generally the most refined methods of husbandry, and therefore should be justified.

To apply the 3Rs (Replacement, Reduction, Refinement) effectively, the project licence holder must be up-to-date with the opportunities that exist in their area of research. The Named Information Officer in each institution should be able to assist with this, as will the Named Veterinary Surgeon and Named Animal Care and Welfare Officer. There is a local Animal Welfare and Ethical Review Body at each Establishment which may also suggest additional 3Rs measures when they review the project application, and when they carry out interim reviews of the progress of the program of work.

Plan of work and protocols

The licence will describe the program of work, making clear how it will achieve the objectives stated. This section of the licence will refer to the different protocols that will be used and explains how these fit into the overall plan of work for the project in order to achieve its objectives.

The protocols are listed after the plan of work, in an index that shows the title, numbers, species and life stages of animals that will be used in each protocol.

Each protocol lists the series of procedures (steps) that need to be carried out in order to achieve the aims of the experiment. If some or all of the animals to be used on the protocol are genetically altered (GA), this is also stated.

In some cases, animals may need to move from one protocol to another for a single purpose, and if this may be required, then it will be specifically stated on both the “sending” and “receiving” protocols. If it is essential that the animal has undergone the procedure described in the first protocol, in order to be suitable for use on the second, then this is considered a single, “continuous” use. One common example of such continuous use occurs when genetically altered (GA) animals are bred on one protocol, then transferred to another protocol to undergo specific procedures. Another example would be implantation of catheters or telemetry devices on one protocol, followed by transfer to a second protocol for further studies.

In some cases, an animal may be “used” more than once on a protocol. An example of this would be an animal used as a blood donor. The second time such an animal is used, because a naïve animal could have been taken to provide blood, that second use would be classified as “re-use” and must be specifically authorised within the project licence. Specific rules need to be followed before re-use can be authorised in order to limit the potential harms which can occur in such cases.

The protocol also indicates whether the various steps are conducted under anaesthesia, or in conscious animals, using a series of codes:

  • AA – No anaesthesia used for any part of technique.
  • AB – Anaesthesia used for part of technique; i.e., animal is allowed to recover from anaesthetic; can be AB (local) and/or AB (general).
  • AC – Anaesthesia used for entire technique; i.e., animal is not permitted to recover
  • AD – Neuromuscular blocking agents are used (must always be given in conjunction with an anaesthetic agent)

Some steps in the procedure may be optional, and this is indicated on the protocol. Some steps may need to be repeated and this should be clear. The order of the steps may be varied, but the protocol is usually clearer when the steps are listed more or less chronologically.

What will happen to the animals after the procedure is completed will be stated (e.g. killing using a Schedule 1 method, or transfer to other protocols). It is often necessary to humanely kill the animals, for example, if tissues are needed for analysis or examination. If an animal does not need to be killed as a necessary part of the study but is experiencing pain, or distress at the end of the procedures, or it is thought that this is likely to occur, then it is a legal requirement that the animal is killed.

If an animal is no longer experiencing any adverse effects, then it may be permissible to:

  1. re-use it in other, unrelated studies, or
  2. release it from the controls of the Act and re-home it,
  3. return it to stock (for example farm animals) or
  4. return it to the wild (if it was a wild-caught animal).

The processes for determining if re-use is permissible and the procedures to be followed for releasing animals are complex, and it is important to discuss them with your facility managers and the “named veterinary surgeon”. The Home Office have published extensive guidance on re-homing animals .

Each protocol also lists the adverse effects (the pain, suffering, distress or lasting harm) that might occur as a result of the procedures, and their likely incidence. It will describe how these will be avoided or limited, for example by providing supportive care to the animal. Each protocol must state clearly the humane endpoints that will be used – these are the clinical signs or other measures that will indicate that the animal will be humanely killed, on welfare grounds, irrespective of whether the scientific objectives of the study have been achieved. The description provided enables the Home Office to judge the severity limits of the protocol. More information on how this relates to your responsibilities as a personal licence holder is described below.

The various sections of the licence should provide sufficient information to enable the Home Office Inspector to make a harm-benefit assessment of the programme of work. If the Home Office considers the harms to the animals is outweighed by the benefits of the work, then the licence is approved. Clearly, making every effort to reduce the harms, and maximize the benefits of the work, make it more likely that a program of work will be approved. Such efforts are also required during the course of the work by a “standard condition” (SC4) on the project licence, which requires the use of the fewest animals using the most refined methods in order to achieve the described scientific outcomes.

Non-technical summary and study protocols

All project licences are required to have a non-technical summary. These provide information to the public on the work performed under A(SP)A and will be written for an intelligent lay audience. They should not contain any information which will identify the place at which the work is being conducted or identify the persons involved, or reveal any intellectual property. The non-technical summary also contains information on the programme of work, its objectives and benefits and the predicted harms to the animals that will be used. It also gives details of the number and types of animal to be used and describes how the 3Rs are to be applied. These summaries are published anonymously on the Home Office website. The non-technical summary can be useful if you are asked to explain the aims of the project, and why they are important, to colleagues, friends or members of the public.

In some circumstances, special conditions may be added by the Home Office, to project or personal licences, or to both licences, and it is important to check whether any special conditions apply to the licences that you (or your licensees) will be working under.

Complex protocols may have a range of optional steps, and it can be quite difficult to assess the progress of an animal during a specific study or to anticipate the potential harms that could occur solely by reviewing the project licence protocols. For this reason, and to promote legal compliance, many establishments require project licence holders to provide study protocols for each batch of animals, which includes full details of the steps of the protocol that those specific animals will undergo. This is of benefit to all involved in both conducting and monitoring the study, including the NACWO and NVS. It also ensures that animal care staff working at weekends have detailed information on each group of animals, and is a practice that should be widely adopted.

Assessing Severity

Each protocol is classified according to the predicted maximum level of pain, distress or suffering, taking account of all the adverse impacts on the animals. The classifications (The Severity Classification) used are mild, moderate, severe or non-recovery (procedures conducted entirely under general anaesthesia).

EU 2010/63 Annex VIII gives the benchmarks against which severity should be assessed and severity classifications for the protocols assigned. For example, single injections of low volumes of non-irritant material, that have no obvious effects on the animals’ health or welfare, would be classed as mild procedures. Repeated injections, of material that could adversely affect welfare (e.g. because of toxicity), would generally be classed as moderate. Administering substances that cause major deviations from normal health, perhaps causing the animal to stop eating, drinking and behaving normally, resulting in a marked loss of body function, such as severe infection, or paralysis, would be classed as severe. Because many protocols use combinations of individual procedures, this classification can be complicated. The Home Office provides a series of examples and further guidance on judging severity.

In order to assess the welfare of the animal, the licensee must be familiar with its normal appearance and behaviour, and initial instruction in this is provided as part of the required training courses for all licence applicants. Once work is commenced, the licensee should take every opportunity to increase their abilities to recognise signs of good and poor welfare in the animals, as this will enable minimisation of the “harms” to the animals during the conduct of work.

A major responsibility of personal and project licence holders is to ensure that animals used in research experience the minimum pain, suffering, distress or lasting harm, consistent with the scientific objectives. Therefore they must ensure that animals do not exceed the severity limits of protocols, (as described in the adverse events section), by taking steps to either prevent this or intervene and humanely kill the animal.

If an animal approaches or exceeds the severity limit on the protocol, then either urgent veterinary care must be obtained or the animal killed humanely and immediately. The personal licence-holder must report promptly to the project licence-holder all instances in which severity limits have been or are likely to be exceeded. In turn, the project licence-holder is required to report these events to the Home Office inspector if severity limits appear to have been exceeded, or are likely to be exceeded. There is a standard format for this report, and your Named Persons will be able to assist with this.

Animals should not be allowed to continue to experience adverse effects that exceed the severity limits of the protocol. It is, therefore, essential that someone competent to kill animals humanely should be available at all times, whether this is a member of the research team or of the animal care staff.

In some circumstances, the adverse effects of a procedure may not be considered to be exceeding the severity limit of the protocol, but an assessment may be made that the scientific data that can be obtained will not be of sufficient quality. For example, infection of wounds can create this situation. As the harms to the animal can no longer be justified by any benefit, such animals must also be removed immediately from the study and killed humanely or, rarely, referred for prompt veterinary treatment. Animals must also be killed promptly if the scientific objectives of the study have been met, and the animals are suffering adverse effects as a result of the procedures.

Actual Severity (severity evaluated after the completion of experiments)

Project licence holders are required to make an assessment of the actual severity which was experienced by each animal used on their licence (i.e the actual “harms”). This assessment must be made in a timely manner, and it is good practice to complete the assessment shortly after the death of the animal or completion of each study.

The assessment may be conducted by the personal licence holder who conducted the regulated procedures on the animals, usually with advice and input from the Named Veterinary Surgeon and Named Animal Care and Welfare Officer. The Home Office have issued extensive guidance on how this assessment should be conducted, and personal licence holders who are involved in this assessment as a designated “suitably qualified person” should read the guidance in full.

The key points to note are:

  1. Each individual animal should be assessed, using the severity categories of mild, moderate, severe and non-recovery.
  2. The Home Office have added an extra category “sub-threshold”, for those animals that did not experience harms that were above the threshold for regulation. For example, breeding genetically altered animals is considered a regulated procedure, but many of these animals have no clinically detectable phenotype. In other words, no harms can be identified. Although the protocol authorising breeding of these animals will often be “mild”, the retrospective reporting of these mice will often be “sub-threshold”. Additional specific advice on severity assessment has been provided by the Home Office.
  3. When making a retrospective assessment of severity, all of the procedure-related harms need to be included. The assessment should identify the highest level of severity experienced, and should not be an “average” over the life-span of the animal. For example, an animal that is considered to be experiencing only mild or no adverse effects for several weeks of a study, but which experiences moderate adverse effects for a short period before it is humanely killed will be classified as moderate.
  4. In addition to taking account of the highest level of severity, the assessment should also attempt to include the cumulative effects of all procedure-related harms. For example, an animal experiencing a series of mild procedures might be assessed as moderate, because of the cumulative effects on its welfare. More details of how to make these assessments are provided in the training module on the assessment of pain and distress.

Retrospective Assessment

Project licences which involve severe procedures, species of particular public interest and certain others will be subject to retrospective assessment. A report on the project will need to be sent to the Animal Welfare and Ethical Review Body (AWERB), and then on to the Home Office. The Non-Technical Summary will be republished including a summary of this report. Some local Animal Welfare and Ethical Review Bodies require both on-going and retrospective review of all project licences, and it is important to check on these local requirements.

Next Article : Personal Licences (PILs)

Updated on 16th June 2021

Was this article helpful?

Related Articles