Animal Ethics

Our long-term ambition is to phase out animal use in all our work. Until then, we are committed to the highest ethics and welfare for all animals used in our activities.

Kerstin Kleinschmidt-Doerr Kerstin Kleinschmidt-Doerr

As humanity, the ultimate goal of all our efforts must be to use our technological evolution to integrate ourselves into the ecosystem, flora and fauna, rather than to continue to consume them. In this context, replacing the use of animals with animal-free methods in research field as well as for commercial purposes is essential.

Kerstin Kleinschmidt-Doerr

Chief Veterinary Officer

Why we use animals

Science progresses quickly and we firmly believe that the continued development of technologies will one day bring an end to use of animals in research and allow our sustainable integration into the ecosystem without compromising patient or environmental safety. We want to be at the forefront of this evolution.

While several animal tests have already been replaced, many alternatives are still in development. We also do not yet have an idea for every animal experiment that is currently urgently needed on how we can replace it. These tests are necessary to find solutions to severe medical problems and to protect the safety of our environment and ourselves – and many are therefore also legally required. Until we have alternatives to all our animal methods, we are committed to enforcing and pioneering the highest possible animal welfare standards in every area of our work.

In addition to the internationally recognized 3Rs principles – Replacement, Reduction and Refinement - we have adopted Responsibility as our fourth animal welfare principle. This reflects our responsibility for all animals in our reach internally and among our service providers and is in line with the latest international thinking on ethical use of animals in research [1].

Read more about our 4Rs in action

We are beginning to see acceptance of animal-free alternatives, and this is a great opportunity for us to innovate to develop those substitutes and engage with regulators to drive acceptance of non-in-vivo tests.

Danielle Elbirt

Global Animal Welfare Officer

Why is animal work necessary?

Almost every significant medical advance of the last century has depended on research involving animals. This research has helped us to scientifically understand how the body works, how diseases develop and to understand what a drug does to that disease and to the body. It is still required to understand that potential treatments are effective and safe for human and animal patients – from surgery to vaccines to cancer treatments. Using animals in research can help us better understand and treat complex diseases such as Parkinson’s and multiple sclerosis.

In addition, some essential products used in research are also derived from animals – for example materials for growing cells in an artificial environment. Animals are also used in mandatory safety testing of chemicals used in everyday products – from paints and dyes to household cleaners – to protect consumers, workers, wildlife and the environment.

As a company we are uncompromising in our mission to deliver the safest and most effective products and services. However, animals are only used by us where there is absolutely no other alternative. We already have many more alternatives today than we did a few years ago, and the number is constantly increasing.

While all this makes animal research a necessity, at least for now, we intend to do it responsibly and transparently. That’s why we’ve brought into force strict ethics and welfare standards to all animals used in our work

Read more about why animals are used in research

Read more about our Approach for a Roadmap to Phase out Animal Testing

The Marseille Declaration

Together we prioritize animal welfare. When it comes to taking responsibility for the animals used in our sphere of impact, we do not compete but collaborate. In 2022, Merck KGaA, Darmstadt, Germany, formed a coalition of pharmaceutical companies to create a common statement that we prioritize animal welfare not only internally but also with all our business partners. Together with other pharma companies leading in animal science and welfare we signed the first joint pharmaceutical industry declaration asking for worldwide implementation of highest possible ethical and animal welfare standards – the Marseille declaration.

Learn more

Exceeding animal welfare standards

Although we aspire not to use animals in our work where possible, we are proud of the high ethical standards we uphold to ensure their welfare.

Not only do we enforce stringent animal welfare standards that often exceed applicable laws, but we also expect our external partners who use animals on our behalf to adhere to those same standards. For example, we require adherence to European Union regulatory animal welfare conditions, which are the strictest in the world, for all non-rodent species used on our behalf.

We ensure that the number of animals used is minimal and there is no alternative available via our animal usage review boards which approve all work conducted by or on behalf of our company involving the use of animals.

As a result, all animals within our reach receive high standards of housing, husbandry, and care – and we continuously improve our animal research processes to enhance the animals’ quality of life.

We are very proud of our colleagues who take such diligent care of our animals and thank them for their important work with the animals and daily loving care and concern.

Read more about our journey from 3Rs to 4Rs

Explore our award winning Rat Colony Cage

The well-being of our animals is very close to our hearts, so we are constantly looking for improvements that increase their life quality. The love for animals is a necessity in our profession.


Animal Technician

Animals used in our work

The number of animals we use changes, and we register a continuous decrease especially when looking at the number of animals used per project. As a snapshot, in 2023, a total of almost 145,000 animals were used in our work, either in our own vivariums or on the premises of organizations contracted on our behalf.

The animals used in our work are primarily rodents (mice or rats) which account for 97% of all animals used in 2023. Other species used are guinea pigs, rabbits, hamsters, fish, non-human primates, dogs, minipigs, tadpoles, goats, sheep, camelids, and chickens.

For our most recent animal use numbers, you can read our sustainability report.

Use of non-human primates

Humans belong to the primate group. Therefore, non-human primates are necessary to understand and model certain diseases that occur only in the primate system. However, non-human primates are used exclusively where the required tests cannot be performed on other species or with non-animal methods.

We acknowledge that non-human primates have a high level of development and a social nature including individual preferences for their environment. Therefore, we do everything we can to ensure special attention is paid to their housing, training, socialization, and environmental enrichment. We want to maximize the quality of life of these animals and reduce their burden to an absolute minimum.

We also strive to avoid the use of non-human primates and are actively researching alternatives, such as human-on-a-chip technologies.

Who carries out animal studies?

We perform the majority (87%) of animal studies used for our work ourselves. But for certain work, we commission contract research organizations (CROs) or partner with universities to conduct animal studies on our behalf. This is sometimes the best choice as they may have particular expertise or animal models that we do not have access to ourselves.

No matter where the work is carried out, we strive to adhere to our global Animal Science and Welfare policy and standards.  

Our vivariums

Curious about our vivariums and our animals?

Learn more

Our 4Rs in action

The 3Rs - Replace, Reduce, Refine were formulated by William Russel and Rex Burch and have been adopted as an ethical framework for improving the welfare of animals used in research around the world [2]. Our company has adopted a fourth principle of Responsibility. You can read more details and examples of how we are putting our 4Rs into action below.

We are committed to our own Merck KGaA, Darmstadt, Germany, 4R approach, whereby each individual life matters. Based on the internationally recognized 3Rs for animal-based research: reduce, refine and replace animal utilization, we aim to create value for our company without compromise on patient or consumer safety” – Kerstin Kleinschmidt-Doerr, Chief Veterinary Officer

Everyone in our company takes responsibility for the animals we use somewhere along the value chain, from start to finish, by always questioning their decisions and doing their best to value every animal.

Frederic Christian Pipp

Global Animal Welfare Officer

Turning our commitments into action

As part of our responsibility for all the animals within our reach, we have global re-homing programs for all species we use in our work.

More information

You can find out more about our animal welfare ethics and standards and our research into alternatives to animal testing below:


[1] DeGrazia D, Beauchamp TL. Beyond the 3 Rs to a More Comprehensive Framework of Principles for Animal Research Ethics. ILAR J. 2021;60(3):308-317. doi:10.1093/ilar/ilz011
[2] 'Russell WMS and Burch RL. The Principles of Humane Experimental Technique. Methuen, London, 1959.'
[3] Brenneis C, Westhof A, Holschbach J, Michaelis M, Guehring H, Kleinschmidt-Doerr K. Automated Tracking of Motion and Body Weight for Objective Monitoring of Rats in Colony Housing. J Am Assoc Lab Anim Sci. 2017;56(1):18-31.
[4] Chang YM, Menges S, Westhof A, Kleinschmidt-Doerr K, Brenneis C, Pitsillides AA. Systematic analysis reveals that colony housing aligns gait profiles and strengthens link between histological and micro-CT bone markers in rat models of osteoarthritis. FASEB J. 2021;35(4):e21451. doi:10.1096/fj.202002009R