The 600,000 Animals Switzerland’s Laboratories Call “Surplus”

Official animal research figures rarely tell the whole story.

In Switzerland, approximately 1.2 million animals are bred or used for scientific purposes each year. Around 600,000 take part directly in experiments.

What happens to the other half?

They are bred for laboratories and killed because researchers decide they are the wrong sex, age or genetic type. Others are simply excess to requirements.

They never participate in an experiment. Their lives are still destroyed by the animal research industry. These animals are described as “surplus”. A cold word for a living individual who was deliberately brought into existence and then discarded.

Harm That Official Figures Ignore

Animal experimentation debates usually focus on what happens during the experiment itself.

How painful was the injection? How invasive was the surgery? How severe was the disease deliberately inflicted on the animal? Those questions are important, but they leave thousands of cages outside the discussion.

Researchers Matthias Eggel, Samuel Camenzind and Paulin Jirkof argue that Swiss law systematically underestimates the harm caused by animal research because it does not properly recognise three things: laboratory confinement, killing and death.

Mice and rats spend their lives in small, barren enclosures that prevent them from burrowing, foraging, exploring and forming normal social relationships. These are not optional luxuries. They are fundamental parts of how these animals live.

Restrictions can cause boredom, frustration, anxiety and chronic stress. Research cited by the authors also links standard laboratory housing with increased rates of anxiety-related conditions, cardiovascular disease, cancer, stroke and premature death when compared with enriched environments.

Yet ordinary laboratory confinement is treated as the neutral background against which the “real” experiment takes place.

There is nothing neutral about a life in a cage.

Death Is Not Nothing

Swiss law also fails to treat death itself as a harm when animals are killed using an approved method.

This depends on an extraordinary piece of moral gymnastics.

The animal loses every future experience they could have had. Their interests are permanently ended. Their only opportunity to live is taken from them.

But because the killing method has been legally accepted, the death can disappear from the ethical calculation.

The authors reject this. They argue that death matters because it deprives an animal of future experiences and prevents any possibility of flourishing.

This applies whether an animal was used in ten experiments, one experiment or none.

Researchers may consider a surplus mouse scientifically worthless. That does not make her life worthless.

Approved Does Not Mean Painless

The process of killing is also treated too casually. Carbon dioxide is widely used to kill rodents, despite evidence that it can cause severe breathlessness, fear and potentially pain before unconsciousness. Cervical dislocation can go wrong, leaving animals seriously injured and still conscious. Barbiturate overdoses may take longer than expected to cause death.

There is no universally accepted killing method that reliably eliminates pain and distress.

Even Switzerland’s veterinary authority has acknowledged doubts about carbon dioxide and funded research into alternatives.

So the system does not merely ignore death. It may also ignore the terror and suffering that precede it.

The Experiments Nobody Needed

The surplus problem exposes something larger.

Animal experimentation is frequently presented as a tightly controlled system in which every animal is used only when absolutely necessary. The existence of hundreds of thousands of surplus animals makes a mockery of that image.

Laboratories breed on a large scale because researchers need animals with particular characteristics. Breeding produces animals who do not match those requirements. They are discarded as a predictable cost of doing business.

Then there are experiments created by the scientific publishing system itself.

A survey of India-based researchers found that 56% had been asked by reviewers to add animal experiments to studies that originally contained none. Researchers reported complying with around one in four of these requests. Another 22% said they had used animal methods solely because they expected editors or reviewers to demand them.

These were not always experiments researchers believed were necessary. Some were conducted to satisfy publishing conventions.

Animal experimentation does not simply produce surplus animals. It produces surplus experiments.

Researchers also reported that non-animal studies were pushed towards lower-impact journals, rejected or placed at a disadvantage when competing for funding.

Governments can announce new technologies and phase-out plans, but progress will remain slow while scientific gatekeepers continue treating animal data as a ritual of legitimacy.

Better Science Already Exists

The alternatives are not theoretical.

Researchers are developing organs-on-chips, human organoids, 3D-bioprinted tissues and AI systems designed around human biology.

One generative AI system, genESOM, was tested using data from a preclinical multiple sclerosis study involving female mice. Researchers deliberately reduced the dataset from 26 mice to 18, causing previously detectable findings to disappear. They then generated synthetic cases that restored key results without producing the same false positives seen with some competing methods.

The researchers were clear that synthetic data cannot replace biological replication in every situation. However, it could reduce the number of animals used in some preclinical studies and prevent demands for additional experiments.

The UK government has also published a roadmap promising greater use of AI, human-cell technologies and bioprinted tissues. Plans include ending some skin and eye irritation tests by the end of 2026 and ending mouse tests used to measure Botox strength by 2027.

The Missing Millions

Even the figure of 1.2 million animals in Switzerland does not capture everyone affected.

Most research regulation remains centred on vertebrates. Countless invertebrates receive little or no meaningful oversight.

A Canadian study involving 959 people found that the absence of oversight for experiments on invertebrates reduced public confidence and trust. Participants still expected animals such as sea stars and grasshoppers to receive substantial protection, even if they generally expected less than for mice and fishes.

That means the statistical blind spot may extend far beyond surplus mice and rats.

Animals excluded from experiments are hidden. Animals excluded from regulation are hidden. Animals killed before data collection are hidden. Animals used in unpublished or failed research are hidden.

Then the industry presents the remaining number as the scale of animal experimentation.

It is not.

It is simply the number the system has chosen to count.

Their Lives Were Never Surplus

The study’s immediate proposal is modest. Housing, killing and death should be recognised as harms when Swiss authorities decide whether animal research can proceed. They should.

But the argument leads somewhere more fundamental.

Once death is recognised as a genuine harm, it becomes harder to pretend that animal experimentation is merely a technical balance between scientific benefit and temporary discomfort. These animals lose everything. Their fear matters. Their frustration matters. Their deaths matter. The future taken from them matters.

An animal does not become ethically significant because a researcher successfully extracts data from their body.

The hundreds of thousands killed without ever reaching an experiment were not surplus.

The breeding was excessive. The system is wasteful. The science is trapped in outdated habits.

Their lives were the only thing that was never surplus.