Animal testing has been a key part of developing medicines and understanding diseases for many decades. However, this practice is becoming more and more controversial.
One major concern is the impact on the animals themselves. Animals used in laboratories often face severe cruelty. They are kept in sterile cages, often alone. They are made to suffer from diseases or injuries as part of the research. At the end of a study, these animals are usually killed.
Animal welfare organizations argue that animals are sentient beings and should not be treated just as tools or objects for science. The American Anti-Vivisection Society (AAVS) believes animals have the right not to be exploited for science.
High failure rate
Beyond the ethical debate, there are significant scientific problems with animal testing. A big issue is that results from animal studies often do not reliably predict what will happen in humans.
This is because there are many differences between animals and humans in their bodies, how they work, and how they handle drugs. For example, paracetamol is safe for humans but toxic to cats. Penicillin is toxic to guinea pigs but very helpful for people.
Morphine makes cats hyperactive but calms humans. Oral contraceptives increase the risk of blood clots in humans but have the opposite effect in dogs.
Even within the same animal species, results can vary depending on things like sex, breed, age, and even the specific laboratory where the test is done.
Also, many serious human health problems like cancer or Alzheimer’s are very different in animals, meaning animal “models” don’t truly copy the human disease.
This lack of predictability leads to a very high failure rate when experimental drugs move from animal tests to human trials.
Sources state that nine out of ten experimental drugs that look promising in animal studies fail in human clinical trials. This high failure rate happens because it’s hard to accurately guess how these drugs will act in people based on tests in animals.
The problems with animal testing have several negative consequences.
High costs
Bringing a new drug to market is very expensive, often costing billions of dollars. The high failure rate after animal testing contributes significantly to these costs, which are then passed on to consumers.
Serious side effects
Sometimes, drugs that seemed safe in animal tests cause unexpected and severe health problems in humans after they are approved.
Adverse reactions to drugs, taken as prescribed, are even listed as the 4th leading cause of death in the United States (US), with a major reason being the poor ability of animal tests to predict human toxicity.
Delayed discoveries
Relying on animal tests can slow down the discovery of treatments that could help humans. Sometimes, potential treatments might not be developed further because they failed in animal tests, even if they might have worked in humans.
For example, the link between smoking and lung cancer, found in human studies in 1954, was dismissed for 30 years because it couldn’t be replicated in animal models.
The polio vaccine breakthrough came from studying the virus in human cells, not animal experiments.
Misdirected resources
Continuing to invest heavily in animal testing can take away money and focus from developing newer, more accurate methods based on human biology.
Current US drug testing rules for humans still rely heavily on animal tests, requirements that date back to 1938. A new law, the FDA Modernization Act 2.0, removed the animal testing mandate and allowed non-animal methods. However, this new law has not been fully implemented, and drug testing still requires animal data.
Traditional tests often involve specific animal species and large numbers of animals, such as rats, dogs, monkeys, rabbits, and mice, depending on the type of test.
Specific controversial practices, like the forced swim test involving rodents placed in inescapable water, have also drawn criticism.
Better alternatives
The FDA Modernization Act 2.0 allows for the use of modern, human-relevant test methods. These new methods include human-relevant cell-based tests, organs-on-a-chip, sophisticated computer modeling and human tissues and organoids.
Human-relevant cell-based tests
These tests use human cells, grown in the lab, to see how they react to different substances. For example, scientists can put a new medicine on the cells and watch what happens.
The tests can help understand if a medicine is safe or if a chemical is harmful. They are useful because they use human cells, so the results are more likely to be relevant to people.
Organs-on-a-chip
These are tiny devices that are made to act like human organs. Scientists use human cells to build these “organs.” For example, there can be a “lung-on-a-chip” or a “heart-on-a-chip.”
Organs-on-a-chip can be used to study how organs work and what happens when they get sick. Scientists can also use them to test new medicines in a very similar way to how the medicine would work in the human body.
Sophisticated computer modeling
This involves using powerful computers to create models of how things work in the human body. Scientists put data into the computer, and the computer can then predict what might happen if someone takes a new medicine or is exposed to a chemical.
Computer modeling can reduce the number of tests because scientists can use the computer to get an idea of how a substance affects a person before doing any lab tests.
Human tissues and organoids
Human tissues are small pieces of human organs. Organoids are tiny, 3D structures grown in the lab that mimic human organs. Both of these come from human cells.
Scientists can use human tissues and organoids to study diseases and test new medicines. Because they are made from human cells, they can give us more accurate information about how a medicine might work in people compared to animal testing.
All these technologies are based on human biology, which is expected to make them better at predicting how humans will react to drugs.
These methods could make drug development faster and cheaper, possibly cutting development time in half. The market for non-animal testing methods is also growing faster than the market for traditional animal testing.
Mental health challenges
Finally, it’s important to note that animal research can also have a significant human cost for the researchers involved.
Scientists, technicians, and students working with lab animals often experience trauma, guilt, and mental health challenges due to harming or killing animals as part of their job.
Many institutions do not openly discuss this emotional toll, creating a “culture of silence”, which can make it harder for researchers to cope and may even lead bright individuals to leave the field.
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