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What is a procedure?
Sub-threshold procedures
Mild procedures
Moderate procedures
Severe procedures
Non-recovery procedures
Reducing suffering in animal experiments

 

What is a procedure?

The term ‘procedure’ refers to any act that may cause an animal a level of pain, suffering or distress equivalent to or greater than the introduction of a hypodermic needle.

The Home Office licenses all scientific procedures in the UK, under the Animals (Scientific Procedures) Act of 1986. It is illegal to conduct any scientific procedures on an animal protected by the law. All living vertebrates (any animal with a spine) are covered by this law. This includes every animal from mice and fish, to monkeys and elephants. The law also covers living cephalopods: squid, cuttlefish and octopuses.

Once a year the Home Office release the number of procedures that have been licenced for the previous year. For more information on the number of animals used in the UK, including severity statistics, see here.

A procedure can be as mild as an injection, or as severe as an organ transplant. Breeding a genetically modified animal is also classed as a procedure, as genetic changes to the normal appearance or ‘phenotype’ of an animal may cause suffering. Procedures can be part of animal husbandry within a laboratory, as well as part of scientific experiments. All experiments involve procedures, but not all procedures are experiments.

 

Statistics on procedures

For the latest statistics on the number of procedures and their severity, as well as other statistics on the use of living animals in scientific research see Animal research statistics.

 

Examples of procedures

Procedures are classified as 'sub-threshold', ‘mild’, ‘moderate’, ‘severe’ or ‘non-recovery’ based upon the degree of pain, suffering, distress or lasting harm that the animal is expected to experience. The expected severity of a procedure is currently determined during the licence application.

Project licences are also grouped into mild, moderate, severe and non-recovery bands. As licences may include more than one procedure, their severity bands refer to the average level of suffering that animals experience during those procedures.

 

Sub-threshold procedures

It is possible that procedures authorised under a project licence could result in below threshold severity. This occurs when a procedure was originally considered to cause above-threshold pain or suffering, but in retrospect this did not occur. This can include:

• breeding of genetically altered animals under project licence authority but without a harmful phenotype
• dosing with a compound in feed where the animals ate normally and suffered no consequences of being dosed

Most procedures are classified as sub-threshold, they account for over 40% of all procedures. See our statistics page for more detailed information.

 

Mild procedures

Mild procedures may cause short-term mild pain, suffering or distress and/or minor changes in well-being or condition. They can include:

• anaesthesia
• non-invasive imaging, like an MRI scan
• short-term social isolation
• taking a blood sample
• superficial surgical procedures

Mild procedures account for over a third of all procedures. See our statistics page for more detailed information.

This video shows animal technologists how to cut small notches in a mouse ear in order to identify it. It is a training video produced by Imperial College London.

 

Blood sampling

This is another training video prepared by imperial College London to illustrate how to take a drop of blood, a blood sample, from mice and rats. You might like to compare the handling and other aspects of this procedure with the older video below.

This video shows a rat being restrained and having a blood sample taken from a vein in the tail. There is no sound.

Blood sampling is one of the most common procedures performed on laboratory animals. From blood samples, researchers can take a wide range of measurements, from the presence of viruses to the activity of the immune system to changes in blood sugar levels.

More video footage of other common procedures being conducted can be found on the Procedures With Care website, which is aimed at training researchers on how to perform these procedures while causing minimal harm and distress to the animal. For example:

• Subcutaneous injection in the rat
• Oral gavage in the mouse (passing a tube from an animal's mouth to its stomach to administer a substance) 

 

Generating antibodies using a rabbit

"This involves catching and restraining the rabbit and giving an injection of a substance that will cause a slight immune reaction (but will not cause sickness). One of the rabbit's ears is slightly warmed up to make the veins stand out so that it will be easier to do the injection. Later blood samples will be taken at intervals and the antibodies extracted from the blood for use in research. Rabbits are  sometimes housed for months or years, and blood samples were taken every couple of months."

Example taken from Openness on Animal Research Dialogue.

 

Moderate procedures

Moderate procedures may cause short-term moderate pain, suffering or distress or long-lasting mild pain, suffering or distress. They can result in moderate impairment in well-being or condition. Examples include

• surgery under general anaesthetic
• causing cancer in an animal
• a modified diet
• exposing the animal to something that they would normally run away from, without enabling them to run away
• forced swim tests (note: swim tests can be classified as severe in some circumstances such as tests of long duration)

Moderate procedures account for approx. 15% of all procedures. See our statistics page for more detailed information.

 

Organ transplants in mice

In this video consultant surgeon, Geoff Koffman explains how research with mice has helped to reduce the problem of organ rejection after a transplant in humans. Researchers transplant the heart from one mouse into a second mouse under general anaesthetic. This enables researchers to study and test potential treatments for the rejection of organ transplants and has led to a significant decrease in the death of humans after transplant operations.

Please be aware that this film contains images of both human and animal surgery.

 

Implanting a wireless transmitter into a rat

"Very small devices are often used to transmit and monitor heart rate from living animals, for example, so that the effects of a drug on the heart can be studied. These devices are surgically implanted into animals and work in a similar way to pacemakers in humans. The rat is given a general anaesthetic, the skin is opened under clean conditions, and the transmitter is surgically inserted and stitched into place inside the body. Painkilling drugs are given before surgery and after the animal has woken from the anaesthetic. The rat will then be given the test drug one or more times, either by injection or by a tube inserted into the mouth and pushed into the stomach, and a receiver will be used to detect and record heart rate."

Example taken from Openness on Animal Research Dialogue.

 

Severe procedures

Procedures where the animals are likely to experience severe pain, suffering or distress, or long-lasting moderate pain, suffering or distress as well as procedures, that are likely to cause severe impairment of the well-being or general condition of the animals are classified as ‘severe’. Examples include:

• any test where death is the end-point or fatalities are expected
• testing a device that could cause pain/death if it were to fail
• inescapable electric shocks
• breeding animals with genetic disorders that are expected to experience severe and persistent impairment of general condition, for example, Huntington’s disease, and muscular dystrophy

Severe procedures account for approx. 3% of all procedures. See our statistics page for more detailed information.

 

Induction of liver failure in mice

Liver failure is an extremely serious condition and remains a major problem across the world. Alcohol, diet, and drugs are major influences of liver injury, and damage to the liver tissue can provoke the body’s immune system into a response. This response may exacerbate the injury, worsening liver problems. Patients with severe forms of liver damage also show defects in their immune system that make them particularly susceptible to contracting infections. Research is needed to help advance our understanding of how the immune system reacts to liver injury and how to prevent the rapid deterioration of the organ due to an excessive immune response. Despite great advances in using liver disease patients and techniques that do not require live animals, the use of animal models is still essential to look at the complicated interactions between liver disease and the immune system. Therefore, mice models of acute liver injury are often used in this area of research.

Acute liver failure in mice can be induced in different ways. Mice may be fasted (with free access to water) to ensure that glutathione levels are depleted, and then administrated with Paracetamol via intraperitoneal or oral gavage. Another way consists of administrating mice with D-galactosamine (Gal) and LPS - the animals reach the acute stage of liver failure within 8-12 hours. During these procedures, anaesthesia and techniques to reduce harm are used wherever possible to minimise suffering.

 

Inducing Parkinson's disease in a marmoset (species of monkey)

"The marmoset is injected in the stomach with a substance called MPTP, which is known to cause symptoms like those of Parkinson's disease. After a series of injections, the marmoset becomes increasingly less able to move and experiences 'tremors' that are typical of Parkinson's. In the end, he is unable to balance on a perch, loses body weight and has to be hand-fed, given extra fluids and kept warm. He then slowly begins to recover and over several weeks regains movement until he is almost physically fit, although still with a slight tremor. The marmoset is then used to test the effectiveness of a potential drug for Parkinson's, which is given by injection into the stomach either once or several times."

Example taken from Openness in Animal Research Dialogue.

This video shows Geoff Butcher, a patient with Parkinson’s Disease, interviewing a scientist who uses Marmosets to investigate Parkinson's disease. The scientist does this by using MPTP to destroy the substantia nigra in the Marmosets. This is the part of the brain that is associated with the fine control of movement. Damage to the substantia nigra causes the symptoms of Parkinson's disease.

 

 

Non-recovery procedures

During non-recovery procedures, the animal is placed under general anaesthetic before the start of the procedure and is humanely killed without ever regaining consciousness.

Non-recovery procedures account for approx. 3% of all procedures. See our statistics page for more detailed information.

 

A sepsis (toxic shock) study in a mouse under 'terminal anaesthesia'

"The mouse is given a general anaesthetic. A surgical procedure is carried out which involves making a hole in the intestine (gut) so that the contents leak into the body cavity and have a toxic effect. A potential treatment for sepsis (toxic shock) is tested while the mouse is deeply under anaesthesia and very carefully monitored. Once the  experiment is over, the anaesthesia is increased until the mouse dies."

Example taken from Openness on Animal Research Dialogue.

 

How is animal suffering reduced during procedures?

The welfare of the animals used in research is extremely important. Efforts are made to minimise the pain or distress experienced by laboratory animals. This is both ethically important, and important for the outcomes of the research. Reducing the suffering and distress experienced by laboratory animals can increase the reliability and validity of experimental results.

The National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) funds research into ways to reduce the need for animals in research.

Adopting best practice for commonly used procedures, such as injections, blood sampling and surgeries, can enormously improve animal welfare. Procedures With Care, a collaboration between the NC3Rs, the Institute of Animal Technology and Newcastle University, has produced excellent videos illustrating best practice during common animal procedures.

This video shows an interview with an animal care technician. She describes the work that she does to look after animals in a research facility and the importance of proper animal care.

Humane killing

When a procedure is over, researchers will often need to conduct post-mortem examinations of animals as part of their studies. This can include examining organs or taking tissue samples for further study.

After some procedures, it may be necessary to kill the animal to prevent further suffering. The person who conducted the procedure must ensure that the animal is killed in a competent and humane way.

Schedule 1 to the Animals (Scientific Procedures) Act 1986 lists the appropriate methods that can be used.

• Anaesthetic overdose
• Exposure to carbon dioxide gas
• Dislocation of the neck
• Concussion followed by the destruction of the brain
• Destruction of the brain by a free bullet (for hoofed animals only)

Methods of killing that are not covered by Schedule 1 require additional licences to perform.

For example, decapitation can only be used on mice and rats in exceptional circumstances. If a researcher needs to collect a large volume of blood that has not been affected by carbon dioxide or anaesthetic exposure, they may decapitate the animal and collect blood directly from the trunk.

It is important that animals are killed quickly and humanely with the least possible suffering, and scientists are constantly re-assessing the methods that are used.

For example, there is much debate surrounding the use of carbon dioxide for killing laboratory animals, with many believing that it is less humane than other Schedule 1 methods. At certain concentrations, carbon dioxide can cause rodents pain and distress. A consensus meeting at the University of Newcastle in 2006 examined the problems associated with carbon dioxide killing, outlined best practice for the use of carbon dioxide, and considered more humane alternatives. The report can be read here.