Animal testing

Animals used in animal testing are known as laboratory (lab) animals. In Germany, the Animal Protection Act (Tierschutz-Gesetz) defines the conditions under which animal testing is permitted. However, these regulations only apply to certain animals. The Act seeks to protect animals that can feel pain and suffering. These animals largely consist of vertebrates and cephalopods. All mammals, birds, fish, and reptiles are vertebrates, i.e., they have a spine. Cephalopods include octopuses, for example.

If animals are killed for the purpose of research, they are also referred to as lab animals. Their killing may be necessary – for example, in order for the animal’s organs to be examined using certain methods.

Every year, the Federal Ministry of Food and Agriculture (BMEL) publishes the number of animals used in animal testing. This figure includes animals that were bred for research purposes but had to be killed. This can happen, for example, if an animal is born without the desired genetic traits or is too old.

Which animals are used for testing?

The majority of lab animals are mice. Fish, rats, rabbits, and birds are also often used in experiments. Dogs, cats, and monkeys make up only around 0.1 percent of lab animals. Compared with other animal species, dogs, cats, and monkeys are also used more frequently in multiple tests (10 to 60 percent of animals).

In 2022, a total of over 2.4 million lab animals were bred, used in testing, or killed for organ removal. In 2023, this figure decreased to 2.1 million lab animals, representing a drop of 13 percent.

Other animals, such as insects or worms, are also used for testing purposes. However, testing on these animals does not require approval or notification of the authorities. As a result, no meaningful data is available in relation to experiments using animals that are not considered by law to be “lab animals”.

Lab animals are bred for a range of different purposes. As part of the breeding process, only certain animals are chosen to reproduce. This ensures that the offspring will have certain inherited traits. These animals can then be used, for example, to:

• investigate certain bodily functions
• identify the origin of hereditary diseases
• understand how the genetic material works in general

For example, there are strains of mice that carry hereditary conditions that also occur in humans – for example, hearing impairment. On the other hand, the “Doogie” strain of mice have a particularly good memory thanks to their breeding. They can be used, for example, to research how learning works.

In other animals, certain segments of DNA (genes) have been inactivated or removed, in a process known as “knock-out”. The functions of certain genes can then be understood by comparing the mice with these knock-outs to those with unaltered DNA. To enable these comparisons, mice are bred with almost identical DNA. The only genetic differences consist of the genes that have been knocked out in some of the mice.

It is also possible to insert fragments of human DNA into the genetic material of a mouse. This process is referred to as “knock-in”. Knock-ins allow researchers to investigate the origins of certain hereditary diseases. The method also enables research into how genetic information controls processes in the body.

Specific genetic changes that have been deliberately introduced in animals do not necessarily lead to them having a predisposition towards a disease or suffering from it. However, mice used in cancer research are particularly susceptible to cancer.

According to the Animal Protection Act in Germany, animal testing is permitted if it contributes towards the development of new drugs, medical applications, or pure research. Animal testing can also be conducted for the purposes of identifying environmental hazards or verifying the safety of drugs and chemicals. 
Official regulations governing the quality control of drugs and chemicals within Europe are compiled in the European Pharmacopoeia. This is the responsibility of the European Pharmacopoeia Commission, which includes, for example, the Federal Institute for Drugs and Medical Devices (BfArM).

Around 75 percent of lab animals are used in pure research and applied research. Approximately 15 percent of lab animals are used to meet legal obligations. This applies, for example, to the safety testing of certain products. A small proportion of animal testing is conducted for educational purposes, as well as for species conservation and environmental protection.

In contrast, no animal testing is carried out for the development of tobacco products, detergents, or cosmetics. Arms are another category of products that must not be developed using animal testing.

What reforms have been introduced in relation to legal provisions for animal protection?

In November 2024, an important milestone towards reducing animal testing was achieved at a European level. The European Pharmacopoeia Commission decided to remove three chapters dealing with animal testing from the European Pharmacopoeia. 

One of these describes the rabbit pyrogen test – in which rabbits serve as test subjects for detecting fever-inducing substances that can contaminate medicines. The other two chapters dealt with a test on cats to detect substances that reduce blood pressure (depressor substances) and a test on guinea pigs to detect histamine, which can cause allergic reactions. As of January 2026, these three chapters will no longer appear in the European Pharmacopoeia. 

These tests on animals are no longer considered as benchmark tests in pharmaceutical testing and have all been replaced by alternative methods.

The welfare of lab animals can be assessed on the basis of various characteristics and behaviors they display. The majority of animal testing is classified as causing only a small amount of suffering for the animals involved. 25 percent of testing is considered to cause moderate suffering. A small portion of animal testing is associated with severe suffering or with the death of the animals involved.

How can the minimization of animal suffering be ensured?

Only people with adequate training are permitted to work with lab animals or conduct testing on them. Before animal testing is carried out, the researchers specify the criteria that will be used to identify any possible suffering for the animals. For example, a special scale is used to classify the facial expressions of mice and rabbits used in testing in order to assess their condition.

The animals are checked on a daily basis, e.g., to quickly detect any weight changes or concerning behaviors. If the condition of an individual lab animal suggests that it is suffering based on the predefined criteria, testing must be modified accordingly. For example, the intensity or duration of the stress on the animals could be reduced or longer rest periods planned to follow on from stressful periods.

What happens to animals that are not/no longer needed?

If lab animals are no longer required in an experiment, researchers check whether they can still be used for other research purposes. Re-homing in private households may be an option, especially for dogs and cats. However, most lab animals are in fact killed.

The legislation is based on the assumption that a painless death is better for an animal than continuing to live in pain or suffering.

• The animals must be killed in a painless manner.
• The precise method with which they are to be killed is pre-defined for each animal species.
• In most cases, their bodies are cremated.
• Under certain circumstances, they may also be used to feed other animals, e.g., in a zoo.

Animal testing helps researchers to understand biological processes and diseases. These include, in particular, complex processes such as:

• the effects of the immune system
• the effects of hormones
• social behaviors
• learning processes

New drugs can be developed on the basis of an understanding of biological processes like these and of how diseases develop. The safety of new active agents can be tested on animals before they are tested on people. This makes testing on humans safer. If the biological processes are already known, alternative methods can then be developed to reduce the number of tests conducted on animals.

What contribution has animal testing made to medical research?

In the past, animal testing has helped us to understand, for example, compatibility between different blood groups in relation to transfusions.

The following milestones in medical history can be largely ascribed to knowledge gleaned from animal research:

• Heart surgery
• Discovery of the drug tamoxifen, which is used to treat breast cancer
• Insights into propofol, which is used as an anesthetic
• Use of therapeutic antibodies in the treatment of multiple sclerosis

The German Animal Protection Act was amended in June 2021 on the basis of a European Directive. The aim was to increase the protection of laboratory animals and to further reinforce the 3R principle:

• Replacement: Replace animal testing
• Reduction: Reduce the number of tests on animals
• Refinement: Improve animal testing

Replacement

To replace animal testing, alternative methods can be used in some areas of research. These include, for example, cell cultures and computer simulations.

Reduce

Tests on animals should only ever plan to use as many animals as are required to produce a meaningful result. Animals with certain genetic traits are usually bred on a continuous basis so that the line never dies out. Only a portion of all animals bred are actually used in testing. To reduce the number of animals that are not used, embryos with the desired traits can be frozen (cryoconservation). This means that breeding can be put on hold for an extended period in which tests are not conducted. At a later point in time, breeding can then be resumed using the embryos. In addition, the people responsible for breeding are fundamentally obliged to determine whether animals not used in testing can be transferred to private ownership or to research facilities.

Refinement

One way of improving animal research is by adjusting the conditions in which the animals are bred and kept. In addition, the way these animals are handled can also be improved to further reduce their suffering as much as possible. For example, the stress of being captured can be reduced by using food to entice animals into a transport container.

Alternative methods to animal testing must be used in all areas in which these alternatives are available. This requirement is enshrined in the German Animal Protection Act. The administrative burden associated with animal testing is usually also greater. In addition, alternative methods are usually more cost-effective than animal testing.

Alternative methods include:

• Cell cultures
• Organoids: Cells cultures that are similar to organs and can be cultivated using stem cells
• Isolated organs
• Invertebrate animals, larvae, and embryos
• Computer simulations of simple systems and cycles

Invertebrate animals (those without a spine), larvae, and embryos are not covered by the Animal Protection Act. However, ethical considerations may also apply to these methods.

Biological processes are complex and can usually only be partially represented using alternative methods. For example, organoids do not have all functions of a complete organ. New methods, such as the multi-organ chip, are currently being developed. However, it is not yet possible to predict whether animal testing will one day be nothing more than a thing of the past.