No. In most research areas, scientists have to use diverse models to answer a specific scientific question. The choice of approach depends on the unique characteristics of the research in question and the best method, or methods, should be chosen in each case. Various strategies, models, methods and technologies are employed in biomedical research, tailored to the specific nature of each research need and animal models remain indispensable for many aspects of fundamental, translational and applied research.
Researchers often use human cell cultures, organoids (complex 3D cell cultures grown in the laboratory), computer modelling, advanced imaging techniques and data from human volunteers or patients. These approaches can provide valuable insights and are increasingly used alongside or instead of animal studies.
However, many areas, such as immunology and neuroscience, require whole-organism responses, as all organs in the body are affected by the biological processes or a certain disease being studied.
Scientists often use data from humans in their studies, if relevant for their scientific questions. Scientists can use, for example, blood samples from healthy donors or donors with a specific disease, and human tissue from biopsies. The data obtained from these human samples can allow scientists to discover important correlations, but these methods do not allow researchers to access causality. To understand if their findings are relevant and gain further knowledge about the mechanisms that could be behind them, and how to harness them to improve human health, more complex studies are often required that might require the use of animals.
Biomedical research using animals does not just benefit human medicine: many developments in veterinary medicine could not have been possible without animal research.
Animals can suffer from many of the same diseases as humans do, including cancer, heart disease, epilepsy and microbial diseases. Animal research is key in finding treatments for these diseases that benefit humans and animals alike.
Vaccine development has been invaluable to modern human and veterinary medicine, and has helped prevent many diseases including rabies, swine fever, foot and mouth disease, myxomatosis in rabbits, and infectious canine hepatitis. Aside from infectious diseases, our pets are increasingly affected by many of the same ‘diseases of affluence’ as humans are, including cancer, diabetes, heart disease and obesity. Animal research is contributing to a better understanding of the biological mechanisms of these diseases, with implications for both human and veterinary treatment. In comparative cancer research, dogs and cats are studied to help understand how spontaneous cancer formation works. Veterinary clinical trials of cancer drugs in dogs and cats can help develop new treatments for people and their pets.
Even though the two might seem similar, there are some important differences when it comes to what they bring to research. Mice and rats have different cognitive and social behaviours, and react differently to stress, handling, and certain drugs and substances, all of which mean that one is more suitable over the other, depending on the type of research. Rats are more intelligent than mice, for example, making them better models for conditions like addiction.
There is evidence that pigs are becoming more favoured over other types of large research animals, such as dogs, which have historically been used as a standard animal model in areas such as training for surgery and cardiovascular research. In brain research, scientists are increasingly using pigs to study brain diseases – sometimes instead of mice, since pigs are more similar tohumans. Pigs are also being viewed as an alternative to monkeys in some areas of pre-clinical research, such as in the testing of treatments for therapeutic antibodies. As the use of pigs continues to grow and replace other animals in research across Europe and worldwide, it seems likely that they will open new doors to what researchers can study and achieve, particularly for human medicine and biotechnologies. As with all species of animal used for research in Europe and elsewhere, consideration of their welfare is required by law to minimise any pain they experience during research, and the principle of the 3Rs (Replacement, Reduction, Refinement) is applied to lower the number of animals used where it is possible and to improve their welfare.
Strict standards govern research with monkeys due to their high sentience and ethical concerns. In many critical fields, there are no other available models that can fully replicate the complex biology of a primate. Where no alternatives exist, the appropriate use of NHPs remains essential for progress in biomedical research and safety testing of new drugs.
A premature ban on monkey research in regions like Europe would halt advances in disease research and undermine animal welfare. Instead, the focus is on steadily reducing the number of monkeys used (through improved experimental design and emerging alternatives) and on refining how studies are conducted. Read more about research using monkey in our feature.
The higher the estimated severity level of a procedure is, the more measures need to be taken to mitigate pain and distress. This concerns much more than only analgesia and anaesthesia during painful procedures. There are numerous ways researchers and animal care staff can make animals feel more comfortable during procedures, such as habituating the animals to the researcher handling or to equipment. For some procedures, animals can also be trained to cooperate voluntarily, which gives them a feeling of control and makes the handling less stressful. Also handling techniques or procedures themselves may be modified to make them less harmful or stressful to the animals, for example cupping a mouse instead of lifting it by its tail.
What happens to animals after a study depends on the type of research and the goal of the study. In many cases, animals are humanely killed at the end of the study so that tissues, organs and body fluids can be examined to better understand the effects of the research.
When animals are no longer required for study, they can be kept for future studies or rehomed if they are healthy and it would not endanger public health or the environment. Before animals are rehomed, they are first socialised to get used to their new lives. The same is true for any wild animals that are returned to their habitat.
All decisions are made with the animals’ welfare in mind and must follow strict regulations and veterinary guidance.
For more than 80 years, animal testing for regulatory safety assessment has been the major route to the development, approval and use of drugs and vaccines in humans, and sometimes other chemicals.
One of the main reasons for animal testing was introduced was a major public health disaster in the USA in 1937. More than 100 people (many of them children) died from taking the antibiotic drug, elixir sulphanilamide, that had been deemed safe in laboratory tests to treat streptococcal infections. However, the failure to test it for toxicity and its effect on a living system meant it overlooked that the formulation in fact contained a deadly poison. In response, the 1938 Federal Food, Drug and Cosmetic (FD&C) Act was passed, requiring a proof of safety before drugs made it to market, and in turn requiring testing in animals as a safeguard that a similar tragedy would not happen again.
As the research community continuously strives to replace, reduce and refine the use of animals (3Rs), New Approach Methodologies (NAMs) are increasingly being developed.
These approaches can currently address some areas of safety testing of new medicines and chemicals. However, NAMs can’t yet address all the fundamental/basic or translational research that leads to medical treatments and drug development, such as how whole, intact organs work and respond to therapies in a living body. For now, it is not possible to model systems and biological mechanisms that are poorly characterised and validated. For example, NAMs are not capable of modelling well biological systems such as the brain and interactions between multiple organs, which are complex and still lack understanding by the scientific community.
In addition, regulatory provisions require the use of animal models for safety testing and this is enshrined in legislation, for drugs applied in both human and veterinary medicine. In the case of marketing authorisations for veterinary medicines, they require the use of animals to demonstrate safety and efficacy in the target animal population.
An EU-wide ban on animal testing for cosmetics has been complete since 2013. This ban prohibits both the practice of animal testing for cosmetics and the import of cosmetics that were tested on animals elsewhere. This is possible because science has progressed far enough to make testing for simpler biological risks such as skin and eye irritation possible with animal-free methods.
There are only limited exceptions related to workers’ safety. Factory workers may be exposed repeatedly and for a long time to chemical ingredients of cosmetics at high concentrations, not only through skin or eye contact, but also through, for example, inhalation. Therefore, animal testing may still be required under the EU’s chemicals regulation REACH to protect their health, when their exposure cannot yet be assessed yet using animal-free models.
Trials for a potential drug, or treatment, tend to always start with rodents (most commonly mice and rats), before progressing to larger animals (such as pigs, dogs and monkeys) if that drug passes the initial tests.
Sometimes a drug will not pass this preclinical stage of testing due to its failure to reach the threshold of effectiveness or because it’s not an improvement comparing with existent drugs – and not because it does not work – and this applies to both studies in animals and methods that do not involve animals. Finally, only when a drug has been confirmed to be safe and effective by these previous tests can it advance to human trials.
Transparency in animal research refers to pre-emptive efforts by research institutions, people involved in animal research and organisations to openly communicate about when, why and how animals are used in scientific studies. This can include regularly sharing information about research using animals, animal care and welfare standards, real-life images and videos of research facilities and the animals used, engaging with the public in outreach activities and discussing both the benefits and the limitations of animal research in scientific and non-scientific events.
EARA encourages the biomedical sector, in every European country, to make a commitment to openness and transparency in its use of animals for research. There are now eight countries with active Transparency Agreements in Europe – Belgium, France, Germany, Netherlands, Portugal, Spain, Switzerland and the UK, and three outside Europe – in Australia, New Zealand and US.
Animal research in the European Union (EU) is strictly regulated under Directive 2010/63/EU on the protection of animals used for scientific purposes, and is implemented nationally by each member state’s competent authorities. The directive is also closely followed in non-EU countries such as Switzerland, the UK and Norway. The Directive’s aim is to protect animals used in research by regulating both the use and care of these animals. Similar standards to ensure the proper regulation and welfare of research animals exist in many other parts of the world, such as the USA, Australia and South Korea.
Research projects involving animals have to be authorised by the local competent authority before they can start. Project applications follow a pre-defined template and include extensive details on procedures and schedules, scientific explanations, ethical considerations and a non-technical summary of the project (see the EARA feature ‘Non-technical summaries explained’). An important component of this assessment is the ‘harm-benefit analysis’ by which the competent authorities assess if the potential outcomes of a project outweigh the harm done to the animals. Once approved, any changes to protocols that deviate from the granted project license require filing an amendment with the competent authority.
Every individual working with research animals must have the right certifications depending on their role: carrying out experimental procedures, designing procedures and projects, taking care of the animals or euthanising animals.
In Europe, this training is required under EU legislation (EU/2010/63 Directive) and includes modules on animal biology, welfare, ethics, legislation, and the principles of the 3Rs (Replacement, Reduction, and Refinement). Training also covers practical skills, such as proper handling and recognising signs of pain or distress, so that relief countermeasures can be applied whenever possible.
Each establishment must have access to a designated veterinarian with expertise in laboratory animal medicine. Veterinarians are responsible for animal health, preventive measures and advising on housing, enrichment, and welfare. They have the authority to intervene where animal health or wellbeing is compromised, including recommending treatment, changes to care practices, or other welfare measures.
The designated veterinarian is a central figure in the animal facility and plays an active role in research projects. They contribute to training and supervision of both researchers and technical staff in animal handling and procedures, and are involved in assessing whether personnel have demonstrated sufficient competence to perform their tasks independently. Veterinarians also advice on project planning and implementation to ensure that animal care and welfare requirements are appropriately integrated throughout the project.