The use of non-human animal models has allowed the fast progression of scientific discovery over the last several centuries. These experiments have lead to great discoveries that have allowed for the alleviation of suffering, sickness, and disease in both humans and animals. Over the years there have been changes in the way we view the rights of animals that have lead to better treatment of models, and discoveries of methods that reduce the need for experimentation on animals. However, we have not yet reached the point that their use is not necessary. If the use of animals in experimentation is to continue, there are many ways of limiting and minimizing suffering while maximizing the benefit from their use.

For the sake of simplicity the word animals in this paper will be used to refer to non-human animals. While it is true that humans are animals as well, we tend to view ethical issues differently when talking about experimentation on humans and non-human animals. For example: Most humans would never dream of eating another human, however over 8.8 billion vertebrate animals are sacrificed annually for use as food in the US alone (NASS 2000). In comparison to that number the 50-100 million vertebrate animals[3] used in scientific experimentation seems extremely small; however, this does not mean there is not an obligation to use efficient and humane practices in the lab.

Views on Animal Rights

The general consensus on the rights of animals has changed over the years. Under the Cartesian theory in the 1600s it was believed that animals are merely automata and cannot be conscious of thought or feeling. This same type of theory was strong among the scientific community even into the 1970s. Even to this day some philosophers and scientists will question whether an animal can feel pain. Others state that vocalization, pulling away from the source of injury, or not repeating actions that would cause pain, may merely be automated responses intended only to aid in animals ability to procreate. This assumption is because it cannot be proven that animals can consciously feel pain, it may not exist for them[1]. To me the question is if we cannot prove it, why do we assume it does not exist? Since animals respond in ways that a human would use to show pain, how can some assume they do not experience it?

Most ethical discussion now focuses on level of cognition, moral consciousness, and theory of self. The attempt has been made to classify at what point in the line of evolution that an animal can be conscious of itself. Different measures used might include the ability to recognize itself in a mirror, being able to learn certain tasks, or whether or not empathy is shown for other species besides its own. These theories often come from working with primates, or having pets and seeing the types of action and reactions these animals have. It becomes hard to deny the intelligence of certain animals after having spent a long time studying and working with them. This has led to the banning of use of great apes for research in many countries and a greater look at how to ethically conduct research with animal models[1,2,5].

Some philosophers question how an animal can even have rights. The natural world has many violences and animals killing animals. How can an animal that seems to have no moral conscience have rights to moral treatment? Others will question if animals need lawyers if laws are put into effect. These ethicists may say that we have an obligation to show compassionate care to animals but that the laws are frivolous and wasteful. In truth, some countries, like Great Brittan, have enacted many such laws. These laws affect the way farmers raise livestock and I am not aware of enforcement having been necessary[2]. Often, laws and regulations just encourage doing the right thing, or provide education on better ways to accomplish the same goals.

At the far extreme are those that state that animals have equal, or even greater rights, than those of humans. The Animal Liberation Front (ALF) has been known to be involved in terrorist actions and shock methods to force their voice to be considered. Bombing of Labs, harassment and even assassination of scientists have occurred in some areas.

Interestingly, it seems that even the activists have a hierarchal view of animals. They will state that all creatures have equal rights but they attack and vandalize mainly labs that work with primates and tend to ignore those with less evolved animals. One professor told me that in graduate school his lab at UCLA (which has been a target for ALF) put a sign on the door that stated they worked with insects in order to keep from being attacked.

Unfortunately tests have not been done only on non-human animals. As recent as a few decades ago, testing was preformed on soldiers, prisoners, and those deemed mentally incompetent. These tests were almost always against their will or without their knowledge. Public knowledge and, in essence, a change in the public viewpoint about the rights of these groups, have pushed for reform and elimination of these types of testing. My question: is there really an ethical difference between testing groups of unwilling humans and having a military draft that forces unwilling men to go to war, possibly to be maimed or killed?

There appears to be a valuation of higher evolved animals over others. Some base it on cognitive differences and others on the apparent moral capability of an animal. Some of it seems to be based on the “cuteness factor.” Animals that tend to be raised as pets tend to evoke unrest when used in experimentation. Far less controversy is stated over use of a cow, but horses or dogs raise disquiet. Interestingly enough, very few people would complain about ridding an apartment complex of mice or rats, but their use in research seems to upset some people. As long as they don’t have to kill and butcher the animal themselves, there seems to be a disconnect that they are eating an animal, while they eat their hamburgers and bacon. Where the line is drawn is not universal, and can vary widely from individual to individual. I also find it odd how many people have trouble with animal testing but no problem with eating meat. It could be that they are not aware of the type of environments in which livestock are sometimes raised. Some animals are raised in conditions that could be considered very inhumane, like 12 chickens being in a cage so small there isn’t room to move. Most laboratory animals have greater freedom and enrichment.

In essence it may boil down to which is the lesser “sin.” To eliminate suffering in both humans and animals we need to learn more, and animal models are still one of the only ways we will learn some things. Is it a greater sin to harm thousands of rodents in experiments, or allow thousands of humans to die when science has the ability to prevent or cure them thanks to advances made through animal experimentation? It can be difficult to draw a concrete line between what is acceptable, and what is moral. We must do the best we can at examining the cost vs. benefit.

Why Animal Models?

Animal testing has been used since at least the second or fourth century where the earliest writings by the Greeks discus its use. Dissection, vivisection and experimentation have taught us most of what we know about anatomy and physiology both in humans and other animals. This knowledge has benefited both humans and animals. Many experiments that are dangerous to be performed on humans can be done on animals and greatly further scientific knowledge.

A common public misconception is that scientists know more about biological systems then they do. In reality, the more we learn, the more apparent it becomes how little we actually know. Although, we have progressed leaps and bounds in the past few decades, we are still a long way off from not requiring animal models to learn new things. The majority of people would not consent to be the first testers of a potentially toxic treatment. By systematically testing treatments on more highly evolved non-human animals, safer testing for humans is achieved.

Technology is developing testing that does not require animals, but a solution is not quick in coming. However, these advances are helping to reduce the amount of animals used in research. Cultures of cells, such as liver cells, can be used to measure hepatotoxicity. If it is too toxic at that stage then it is known that testing does not have to go further; however, biological systems are much too complex to account for every variable that will occur inside the human or animal body by using simple cell cultures.

Computer programs are being developed that also are able to cut down on the amount of animals needed for testing. Computer models and algorithms based on data from decades of testing are able to predict much about how a chemical will function, or how cells connecting in the brain in a certain pattern may function. Unfortunately, in many ways these technologies are still in the early stages. They can greatly improve the plausibility of a hypothesis though, and allow for less testing on animals. Data from wet lab testing can then be fed back into the computer algorithms and improve results, often within the same lab or center, greatly increasing the overall efficiency of the research. There is a strong possibility that in the future we may develop this technology to the point where testing is no longer needed, but there is no way of telling when this will happen. We currently use far less animals in testing then we did even a few decades ago. As technology and methods improve, we should find even less for animal testing.

Improvements in animal models

With the continued need for animal models, maybe the big question should be what is the most ethical way to treat animals used in research. Care for animals involves many different facets. Much can be done to recognize and alleviate distress in laboratory animals. The 3Rs (Refine, Reduce, Replace), developed in Great Brittan, tries to take much of this into consideration[4,5] and its influence is now seen in labs across the world.

Understanding of the difference between stress and distress is necessary to continue. The two words should not be used interchangeably. Stress is a real or perceived perturbation to an organism’s physiological homeostasis or psychological well-being. Distress is a negative state in which coping and adaptation processes fail to return an organism to physiological or psychological homeostasis. All organisms go through stress in many forms but are normally able to adapt and recover. Being able to recognize the difference between stress and distress can be a challenge. Many factors may affect differing reactions to distress. Age, gender, genetic traits (including transgenic modifications,) rearing and postnatal separation, psychological state, and housing conditions can all affect both the tolerance for stress, distress and the way in which stress and tolerance are presented. Care is taken to try to eliminate as many variables as possible, but there is still variation from lab to lab.

Refinement involves many aspects of research methodology as well as husbandry. Reviewing techniques use in research to bring about the minimal amount of pain, stress, or suffering is important. It is true that it is not always possible to give medications to a lab animal that will prevent pain, as the chemicals may interfere with results. It is necessary however to define an endpoint that is as humane as possible, so that the animal may go through as little suffering as possible4. Even having a clearly defined protocol of when to euthanize or treat can greatly cut down on the suffering of lab animals. A better understanding of distress mechanisms may help to define earlier end points and get appropriate data.

Housing and feeding can be issues to address as well. Sometimes a larger cage can be a great relief of stress, though some labs have limited space for animal care. Proper nutrition and opportunities for enrichment will also provide more relief and better coping mechanisms. Knowledge of the natural habitat of a species and whatever can be done to mimic that environment, from temperature, opportunities for socialization, lighting, or water quality can go a long way to reduce stress. The effects of chronic stress have been thoroughly documented enough to know that avoidance should be undertaken.

Reduction limits the amounts of animals needed for a study. The use of pilot studies with limited specimens to refine techniques and understand how results should come forth can help get an accurate understanding of results. Having good statistical method can tell ahead of time how many specimens are necessary to get relevant results. The development of new techniques can improve results and further reduce, or eliminate, the population of subjects necessary.

Replace is primarily about developing new technologies that allows the testing to occur without the use of animal models. Cell cultures have been, and currently are being developed, that can give a great deal of information without the use of whole organisms. For example, tumors can be grown in cell cultures, as opposed to in vivo, for the majority of tests for studying anti-tumor activity against cancer. If the study is successful, toxicology testing can be tested in cultured liver cells, as well as other cell lines. Much data can be gained to test the efficacy and toxicology prior to testing in animals. This technology has not replaced animal testing for the entire testing from discovery to market, but huge amounts of animal testing is becoming obsolete. In the future, the predictability of computer modeling programs and cell culture tests among others may make animal testing a thing of the past.

Funding Issues

Throughout this paper technologies have been discussed that may one day replace animal testing. As with all research, a great amount of money is required to fund it. The development of new technologies can be an extreme expense. Unfortunately most funding that goes to research is considered an investment that is expected to have a pay off forthcoming. Many replacement technologies and even research on recognition of distress, or health and well being of animals in laboratory programs have trouble getting funding. Let’s face facts; mice are cheaper than developing the technologies necessary to make them non-vital.

As scientists are fighting to get funding for their projects, it can be difficult to get enough funding to cover any extra expenses. Training lab personnel, hiring lab animal vets, better habitats, and enrichment, can sometimes be overlooked due to lack of funding. In reality we are in an era where discovery is coming faster than ever. With knowledge of mapped genes, more information every day on connectivity and morphology of neuron in the brain, better understanding of membrane channels, and so much more. We are in a time of exponential growth of knowledge. The problem comes due to there being a limited amount of funds available to spend. People want to see an immediate payoff for the funds they grant, not small improvements in methods that may one day eliminate animal use in laboratories for the sake of animal rights.

Organizations like PETA and the Animal Liberation Front spend incredible amounts of time, effort, and money on trying to stop animal experimentation, but offer no alternatives to their use. Problems can’t be fixed by use of force and shock ad campaigns. People in these types of organizations are in them because they believe that they are doing a good thing. How much more good could they do, if instead of forcing money be used to beef up security and hire guards, they focused their time, energy, and funds on fund raising for research on ways of improving the well being of lab animals, and finding novel ways and technologies to use non animal research? Scientists are trying to better the world too, by trying to prevent and cure ills for humans and animals alike. To cause fear and stress in the lives of these people cannot be considered ethical either.


Laboratory scientists and associates can educate themselves thoroughly on the needs of the different animals they care for. Developing protocols for care and maintenance, as well as looking for ways to improve their experimental design to limit suffering and develop humane endpoints, should be an important part of the development process. Looking for ways to reduce the use of animals in procedures and trying to develop new methods could make a huge difference in future studies. Knowledge of signs of stress and distress is key in eliminating unnecessary suffering.

While the use of animal models is still necessary, measures can be taken to assure the best possible methods, and eliminate suffering. Development of new methods and availability of new sources of funding could further reduce or eliminate the use of animal models in research.

[1] Frans De Waal. Primates and Philosophers. Princeton University Press. 2006
[2] Claire Andre, Manuel Velasques. Of Creatures Great and Small. Issues in Ethics. 1988, 1-3
[3]Flossos Andreas. Ethical Issues in Animal Research, The Greek E-Journal of Prerioperative medicine. 2005, 3, 1-5
[4]Peter A. Ward et al. Recognition and Alleviation of Distress in Laboratory Animals. National Accadomies Press. 2008
[5]Editorial. Animal Research and the Search for Understanding. Natural Genetics, 2006, 38-5, 497-498
[6]Peter Singer. Writings on Ethical Life. HarperCollins Publishing. 2000