LivingAnimal experimentation, why does it still exist?

Animal experimentation, why does it still exist?


Today is International Laboratory Animal Day , and the goal is to make society aware of how important their role in research is. In recent decades we have seen a notable advance in the technology and techniques available, but some animal models are still essential in certain studies. Why not stop using laboratory animals? What advantages do they have compared to other current models?

The complexity of an organism

The investigation is a race that is much more like a marathon than a 100 meter hurdles, although it also faces numerous obstacles. One of the engines that drives studies and research projects is to answer questions , whether it is to elucidate why some biological processes occur, how certain diseases develop or what treatments to develop to cure them.

To answer these questions, it is necessary to design appropriate experiments and, in most cases, the decision to use one or the other is affected by the available methods and techniques . Often, the creativity of researchers must adapt to reality that is conditioned by technological advances and the knowledge of the scientific community.

Artificial models are sometimes useful in mimicking natural conditions in some respects. This branch of research has developed especially in recent decades thanks to scientific knowledge and technological advances. However, why haven’t new technologies replaced animal models?

The reality is that there are still no artificial models that perfectly mimic the complexity of a living organism . We still don’t know many internal processes or how the different parts of a mammal communicate, and the ones we do know are very difficult to replicate.

Most of the questions sought to be answered are related to diseases or treatments in humans. In both cases, effects on the whole organism must be considered, and artificial models are insufficient because they are limited to a few cells or an organ.

To understand how a drug is tolerated or distributed in humans, we need to introduce it into a similar system, with organs, blood circulation, degradation, and a thousand other processes. This simply does not exist artificially and here comes the alternative: animal models .

Models that cure diseases

Animal models are very diverse and are designed according to what questions they are going to answer. A well-known example is the use of mouse models to test the efficacy, tolerability, or dosage of new treatments , such as vaccines . However, mouse models can help in many other fields of research.

For example, to study “diseases” that do not exist in humans . Although this may not be intuitive, it is very useful for understanding the functions of some cells such as mast cells, one of the main cells involved in the immune response . No person has been found who does not have mast cells, and this indicates that they must be essential.

However, when these cells are the cause of a disease, it is not entirely clear what happens to them and how to fix it. An example is mastocytosis, where mast cells are “hypersensitive” and are activated by any stimulus, which can cause anaphylaxis and death .

In order to evaluate how mast cells work, a mouse model called “Hello Kitty has been developed, which has a particularity. These mice have a genetic modification so that all their mast cells can be eliminated and, although the mice generated are viable, they have some characteristics.

Among other things, these mice have intestinal problems and are unable to fight off parasitic infections . Having these models that do not exist in humans and are impossible to replicate with cells, helps us to understand the communication of the immune system and test drugs for diseases such as mastocytosis.

The process of change

This is just one example of many types of models that allow us to continue investigating and answering the questions that keep coming up. However, the entire scientific community is concentrating efforts to reduce animal models to the minimum possible .

There are more and more regulatory measures that review all animal trials and ethics committees are updated based on new evidence. There is still a long way to go and the alternative models available still do not match some animal models.

Until we manage to eliminate them completely, we must continue to investigate in an ethical and moral way with the models that continue to allow us to cure diseases. Without going any further, today a certain normality can be resumed in our routines thanks to the development of vaccines against COVID-19, and all of them have passed through animal models.


Mukai et al. 2017. Differences in the Importance of Mast Cells, Basophils, IgE, and IgG versus That of CD4 + T Cells and ILC2 Cells in Primary and Secondary Immunity to Strongyloides venezuelensis. Inject Immun . doi: 10.1128/IAI.00053-17

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