Technical terms glossary

This is a term often used when discussing the use of animals in ‘regulatory testing.’

An adverse outcome pathway (AOP) is a model that uses knowledge of biological pathways and systems to help identify the events required to produce a toxic effect when an organism is exposed to a substance. AOP Frameworks provide guidance for the use of non-animal approaches for assessing the toxicity of chemicals and safe drug development, and reduce reliance on animals.

Any harmful, unintended reaction that results from the administration of a drug or medicine.

This term is used to refer to non-animal models or a combination of tests and methods that replace the need for animal experiments, such as in vitro and in silico techniques. These may also be referred to as non-animal or replacement methods/approaches or NAMs (New approach methodologies). In regulatory safety testing, these non-animal approaches are sometimes described as New Generation Risk Assessment (NGRA).

Learn more about some of the alternatives to animal research currently being used by researchers.

Sometimes alternative is also used to describe an alternative animal model which is not regulated and therefore viewed to suffer less, such as an invertebrate This is sometimes referred to as ‘Partial Replacement’.

Substances which relieve pain (e.g. paracetamol) These should be given to animals in research, where possible, as a ‘refinement’ to reduce suffering.

A preference for animal research-based approaches over non-animal approaches. This can occur for many reasons including a lack of confidence in new methods when compared to many years of animal tests or data in a specific area of research or testing. This bias can be seen in the funding and publication systems when animal approaches are viewed more favourably.

Learn more about animal bias in scientific publishing.

Under existing legislation that regulates animal research, this is any procedure applied to a protected animal for a qualifying purpose, such as any scientific, research, testing, or education. Also referred to as a scientific or animal procedure.

Learn more about what’s meant by a ‘procedure’ in animal research.

The view that animals have the right to be free from human use and exploitation. This includes the right not to be used for breeding, food production, for use in research or kept as pets.

Is the legislation that regulates the use of protected animals in scientific research in the United Kingdom. ASPA sets restrictions on what animals can be used, how they can be used and how they can be killed.

Learn more about the Animals (Scientific Procedures) Act 1986 (APSA).

Refers to the well-being of an animal. Under the Animal Welfare Act to ensure good welfare, animals in captivity or under human control are required to be free of:

• hunger and thirst
• discomfort
• pain, injury or disease
• Inability to express normal behaviour
• fear and distress

Legislation passed in 2006 that places a duty of care on people to ensure they take reasonable steps in all circumstances to meet the welfare needs of animals under their care to the extent required by good practice. They must take positive steps to ensure they care for their animals properly and in particular must provide for the five welfare needs, which are:

• Need for a suitable environment
• Need for a suitable diet
• Need to be able to exhibit normal behaviour patterns
• Need to be housed with or apart from other animals
• Need to be protected from pain, suffering, injury and disease

This does not apply to invertebrates(excepting octopus), embryonic animals, wild animals (unless protected) or research animals.

Learn more about legislation and regulation in the UK for animals used in scientific research.

Substances used to treat bacterial infections (e.g. penicillin).

Specialised proteins produced by white blood cells in response to the introduction of a ‘foreign’ substance (antigen) into the body. The antibodies have the ability to recognise specific antigens and to bind to them very tightly. This ability to bind to specific molecules makes them ideal locators for use in cell research, where they are used to latch onto, isolate and help identify, molecules of interest in and on cells. Antibodies have become one of the most important tools for studying protein function in cells. Many antibodies used in research have historically been, or still are, animal-derived.

Applied research is any research that may help advance the practical real-life application of science to solve specific problems. This could be advancing the the creation of a new product or procedure, for example helping to develop a new vaccine to prevent infection of a specific virus.

Translational research is a term often used alongside or instead of applied research. It is a more systematic approach to creating practical applications which may involve a multi-disciplinary approach. In  medical research is often used to refer to the translation of basic research into benefits for human health.

Also known as fundamental research, basic research aims to expand knowledge or understanding without immediate applications. This can include exploratory or non-hypothesis driven research with no predicted outcome or aim. In biomedical research this includes research to increase knowledge of physical, chemical and functional mechanisms of biological processes or disease.

Basic research is the biggest area of research and testing that involves scientific procedures on animals in the annual statistics published each year for animal use in science.

The growth and maintenance of living cells outside the body. This requires the provision of favourable artificial conditions to encourage cells to grow, such as the right temperature, nutrients and pH levels. This varies for different types of cell. Cells used may be obtained directly from living tissue (primary cells) or existing cell lines. Cell culture is an example of an ‘in vitro’ system.

Learn more about in vitro methods as an alternative to animal research.

Thread like structures found within the nucleus of cells containing genetic information (DNA) in the form of genes. Different species have different numbers of chromosomes.

The signs or symptoms of an illness, disease or injury that a doctor, vet or scientist can see.

A type of research study that tests how well new medical approaches work in people. These studies test new methods of screening, prevention, diagnosis, or treatment of a disease.

Cloning is the process of producing large numbers of genetically identical cells from a single cell, as is often required in cell culture. All of the cells of a clone have the same genes and produce exactly the same antibody. Whole organisms can also be cloned.

A term used within a laboratory animal context to mean a commitment to animal welfare, care of staff, transparency, and scientific quality. Culture of care is about going beyond what is expected by law to ensure compassion and respect to both the animal used in research, and the staff using them.

Learn more about what a culture of care is.

A group of small protein molecules including interferon, interleukin and growth factors, that are produced by cells of the immune system during inflammation. Cytokines are involved in signalling between cells, causing effects both locally and throughout the body. If overproduced by the immune system in response to another condition this can produce a ‘cytokine storm’ effect.

A large molecule that acts as the hereditary material by carrying information coding for all the characteristics and functions of an organism.

The most common and severe type of Adverse Drug Reaction and is a common cause of liver failure. DILI is difficult to predict in new, or existing populations because it only affects a small percentage of the population. It is thought to be mediated by the individual’s immune system and influenced by their genetics.

How effectively a drug produces the desired result. Animal tests are used to give an indication of the efficacy as well as safety of the candidate drug.

“Normative” i.e. how things should or ought to be, how to value them, which things are good or bad, which actions are right or wrong.

• Animal ethics: whether we ought to do something or with welfare, how we ought to do something.

Investigations to discover something new, prove an idea or test a hypothesis.

A pre-planned set of methods devised to answer a research question without bias or error. Experimental design is particularly important in animal research to ensure animal numbers required are reduced to a minimum and welfare prioritised whilst allowing the scientific objectives to be met.

Learn more about experimental design.

Foetal Calf Serum (FCS), or Foetal Bovine Serum (FBS) is used to provide nutrients for growing and developing cells in the lab.

Serum is collected directly from a calf’s heart soon after their pregnant mother cow is slaughtered. If the foetus is not dead or unconscious at the time of collection, then they are likely to suffer.

As serum is a biological product, it varies from batch to batch, so this can affect quality of experimental data.

Please read the Cassotta et al 2022 paper on the worldwide use of FBS to see the scale of the issue, and Versteegen et al 2021 to learn more about the animal welfare and ethical issues associated with this product.

Genetically altered (GA) is a term used to describe animals that have had their DNA altered for example by adding, removing, or modifying specific genes. The resulting changes in DNA can have a positive, negative, or neutral effect on the physical characteristics of an organism. In scientific research this is normally a deliberate change to model a disease or investigate the function of a biological process. These animals are referred to as genetically altered (GA), but are also known as genetically modified (GM) or genetically engineered (GE). The first GA mouse was created in the 1970s. When creating GA animals there is the potential for genes other than those being targeted to be changed. This has the potential to cause unplanned suffering to the resulting animal.

Around half of all regulated procedures each year are for the creation and breeding of GA animals, before they are used in research or testing.

Changing animals, by inserting, mutating or deleting genes or parts of chromosomes. These animals are said to be genetically altered (GA). See ‘Genetically altered’ for more information.

A supporting document providing detailed guidance on how ASPA should be administered and enforced. It includes further details on what constitutes a regulated procedure, what animals are protected, licensing requirements, principles of the 3Rs, euthanasia methods, rehoming and re-release, housing and husbandry, AWERBs, inspections, and penalties for non-compliance.

Learn more about ASPA and its surrounding regulation.

Showing concern for animal well-being.

Identifying the earliest point at which a procedure will be ended to minimise pain, distress or discomfort, whilst allowing the scientific objectives of the research to be met. While humane endpoints often result in the euthanasia of an animal, they are set as an endpoint to a procedure, not an animal, and can also be applied in the form of predetermined pain relief.

Learn more about what a humane endpoint is.

A complex system involving protective cells, tissues and organs in the body, which specifically recognise and destroy foreign organisms which otherwise could cause harm.

Antibody-based methods that allow the measurement of very small quantities of substances, such as cytokines or hormones, in blood samples.

Genetically similar animals, produced as a result of the repeated mating of closely related animals. Often used in animal research or testing due to the reduction of biological variation between individual animals.   (See Outbred strain).

Substances that are used to make a finished product. E.g. Chemical ingredients may be found with in a household product.

Methods that use computers, mathematical models and simulations to predict, for example, human responses to a compound, or to model the progression of disease and treatments within the human population.

‘In glass’ experiments are carried out outside the body of an animal, in for example a test tube or culture dish. In vitro research is generally referred to as the manipulation of organs, tissues, cells, and biomolecules in a controlled, artificial environment. The characterisation and analysis of biomolecules and biological systems in the context of intact organisms is known as in vivo research.

Latin for ‘within the living.  The characterisation and analysis of biomolecules and biological systems within a living organisms. Often used to describe research using animals.

Reversible damage to tissues, such as the eye and skin, causing redness and soreness.

Brain imaging technique which detects signals given out by the brain when a person is awake and records them as an image on a computer.

Chemical and physical processes within the body that alter a chemical.

Genetically non identical animals, produced by breeding at random or selecting parents that are not closely related. (See inbred strain). This increase genetic diversity within the population which increase variability, but is also more representative of a population, such as people.

A concept linked to the implementation of the 3Rs where suffering is reduced in experiments by using for example an invertebrate species (such as flies, moths or worms) that are not perceived to be sentient, or therefore suffer in the same way a mammal might. This term is also used where animals have been killed with the sole aim of providing primary animal tissue for research. These animals will not have been used or suffered in any regulated scientific procedures prior to this.

A progressive nervous disease occurring most often after the age of 50, linked with the destruction of brain cells that produce dopamine. Symptoms include muscular tremor, slow movement, partial facial paralysis, strange posture and weakness.

Learn more about human-relevant approaches to studying Parkinson’s.

Trials/tests

Literally “after death”. An examination of a dead body to discover the cause of death.

A test or experiment. See ‘regulated procedure’ or ‘animal procedure’ for specific references to scientific procedures on animals.

Animals are protected under ASPA. Vertebrates (i.e. animals with backbones), other than humans, from halfway through their development in the womb (mammals) or egg (birds and reptiles), or when they are able to feed by themselves (amphibians and fish). Cephalopods (octopuses and squids) are also protected.

One of the 3Rs principles.

Reduction requires that a minimum number of animals within a scientific experiment or project are used to achieve the aim.

This is often achieved through experimental design to ensure that enough animals are used to achieve scientifically robust data, without unnecessary animal use.

One of the 3Rs principles.

Where regulated procedures on animals are deemed necessary in research or testing, under the 3Rs principles the suffering to animals must be minimised through the refinement of husbandry, handling and experimental techniques to reduce the amount of pain and distress caused to laboratory animals. This includes things such as increasing housing size and enrichment, or keeping animals in groups, it also refers to adapting procedures, for example by using pain relief, to minimise potential suffering.

Replacement refers to the principle of use of alternatives can be defined as methods, strategies and techniques, such as cell culture, that do not require live animals.

When the term is used in the context of the 3Rs as required by law, it refers to the use of regulated scientific procedures on animals as a last resort. In other words the replacement of animal use.  Replacement is the first of the 3Rs principles that should be considered.

Under existing legislation that regulates animal research, this is any procedure applied to a protected animal for a qualifying purpose, such as any scientific, research, testing, or education. Also referred to as a scientific or animal procedure.

Learn more about what’s meant by a ‘procedure’ in animal research.

A list of humane methods of killing laboratory animals and approved means of confirming that the animals are deceased. Schedule 1 killings are not regulated procedures and therefore do not require a project license to perform. The method of killing used depends on the species, size and age of the animal.

Learn more about Schedule 1 killings.

A section within the Animals (Scientific Procedures) Act 1986 concerning the protection of confidential information. Under Section 24, the Home Office cannot release any information received in confidence under ASPA.

Learn more about what Section 24 is.

A word used to describe the ability to experience feelings and emotions e.g. to feel pain and suffer as a result. Not all animal are recognised as ‘sentient’ within the law.

Animal research legislation has historically included animal species that are considered ‘sentient’. Our knowledge and understanding of sentience is evolving with more invertebrate species being recognised as such.

The 3Rs stands for the principles of Replacement, Reduction and Refinement, as alternatives to the conventional use of animals in laboratory-based research. They were first described in 1959 as guiding principles for more ethical use of animals in research.

The 3Rs are used worldwide by researchers, universities and are a legal requirement under legislation such as the Animals (Scientific Procedures) Act 1989 (ASPA). The 3Rs’ primary aim is to replace animals with non-animal methods where possible. There’s also a commitment to improve animal welfare where animal use is deemed unavoidable by regulatory bodies or researchers.

The 3Rs stand for: 

• Replacement – Where alternative techniques, methods and strategies are available that do not require live animals, they should be used instead
• Reduction – Refers to the reduction of animals being used in an experiment to the minimum required to achieve the aims 
• Refinement – Refers to the requirement to refine experimental procedures and husbandry practices to minimise pain, suffering and distress for the animals involved 

Level of poisonousness; potential to cause harm.

Taking tissue or a whole organ, such as a kidney, from a donor individual and surgically introducing it into the body of a patient to replace a defective tissue or organ.

Read about our views on xenotransplantation.

Carrying out surgical experiments on living animals.