Key Criticisms
Not supported by evidence
“The claim that animal experimentation is essential to medical development is not supported by proper, scientific evidence but by opinion and anecdote. Systematic reviews of its effectiveness don’t support the claims made on its behalf. “
(Pound, P. et al. 2004. British Medical Journal 328, 514-7.)
Surprisingly, scientists do not regularly review the predictability of animal tests as part of their work- they assume animal tests work based on certain similarities with humans and long history of use. It is not enough to come up with one or two examples of where animal tests appear to have been helpful. To be an effective way of doing science, animal tests need to be consistently predictive. Just because animals were used as part of the drug discovery process also does not mean that they had to be used, nor that they were a key part.
“Virtually every medical achievement of the last century has depended directly or indirectly on research with animals.’ …Despite its endorsement by leading academic bodies, it is far from clear that the statement has been, or even could be, formally validated.”
(Medical progress depends on animal models - doesn't it? Journal of the Royal Society of Medicine 2008;101:95-98).
Not predictive
The few studies that have been done to look at how predictive animal tests are of human effects have been damning (see animal tests on trial). Due to the high variability of the results between sexes, species and laboratories, high doses used, high stress levels, poor methodology used in addition to species differences it is not surprising that animal tests do not appear to accurately predict human effects. Indeed if you evaluate these studies it is fair to say that overall animal tests are predictive of human reactions less than half the time. You might as well pay someone to sit in a room and toss a coin.
Inconclusive
Because animal experiments don’t provide definitive data about humans, scientists, officials or companies can -and do- dispute their relevance when it suits them to do so. For example pesticides manufacturers are currently disputing rat studies that suggest a link between pesticide use and Parkinson’s; “They have seen effects in rats. We don’t think they have any data that would link disease to humans.”
(Daily Mail, 09/08/06)
Other examples where animal tests exacerbated years of dialogue and debate (and no action) include asbestos, smoking, saccharin and bisphenol A. Fears about nanoparticles, GM food, and endocrine disrupters are currently being used to justify animal tests but sadly it’s unlikely that until adverse effects are seen in humans real governmental action will be taken.
This lack of faith in the predictability of animal tests possibly explains the high rate of non-use of animal data. Recently conducted studies are showing a horrendous proportion of animal tests are not actually used in the ways that we would expect them to be (to lead to human trials if they suggest the treatment works safely, to not lead to human trials if they do not). Even more horrifically, there are many examples of where animal tests are conducted at the same time as similar studies on humans by other researchers (see animal tests on trial), suggesting that animal tests do not play the vital role we are led to believe they do.
Inefficient
Due to the lack of predictability of animal tests and sheer volume with which they are conducted, the entire process is extremely ineffective, wasteful and expensive. For example, the rat cancer bioassay takes 5 years from start to finish, uses 860 animals and costs between $2–$4 million.
(Longer Rodent Bioassay Fails to Address 2-Year Bioassay’s Flaws. Environmental Health Perspectives 2008; 116; A516-7.)
Add in the prospect that the animal tests are not predictive or even used properly to inform medical practice and you have a highly inefficient, inadequately uncontrolled system. Reliance on such a system would not be tolerated in other sectors of professional business. And yet this is probably the most important area of research endeavour.
“Currently, nine out of ten experimental drugs fail in clinical studies because we cannot accurately predict how they will behave in people based on laboratory and animal studies.”
(Mike Leavitt, Health and Human Services Secretary, Food and Drug Administration Press Release Jan 12th 2006)
This means that even after all the animal tests, less than 1 in 10 drugs actually make it to become prescription drugs. This is a massive failure rate, which the FDA, one of the main drug regulators in the world, acknowledges.
Despite using over 100 million animals worldwide every year, less than 30 brand new drugs come onto the market on average every year in the US (the largest pharmaceutical market). This shows how hugely wasteful animal testing is.
(Anon 2008. Editorial: “Only 17 new molecular entities were approved by the US FDA in 2007, a fall from 53 in 1996”. Science 320, 1563)and Estimates of worldwide laboratory animal use in 2005. Alternatives to Laboratory Animals 36, 327–342.)
Failing
Despite considerable effort over many decades creating animal models of conditions like stroke, Alzheimer’s, HIV, Type 1 diabetes and multiple sclerosis, we do not yet have reliable, effective treatments. Animal testing also failed to prevent the Vioxx and TGN1412 drug trial disasters.
Old fashioned
Drug development today is concentrated on highly targeted cell and gene-based therapies. The differences between species at these levels make it even more difficult and dangerous to use animals to predict human outcomes. We need 21st century tests for 21st century medicines.
For example, the 2006 Northwick Park drug trial disaster (TGN1412) was testing a novel monoclonal antibody treatment. Tests on monkeys at 500 times the dose failed to predict the severe side effects seen in all six of the trial volunteers. Subsequent tests in the test tube were quickly performed that could have actually predicted the effects.
(Duff, G.W. (2006) Expert Group on Phase One Clinical Trials: Independent report to the Secretary of State for Health. 7 December 2006. The Stationery Office; London UK. P.65.)
“These types of drugs [biologicals] make up more than 50% of new drug applications. We can't use toxicology that is 60 years old.”
(Prof. Thomas Hartung, former head of the European Centre for the Validation of Alternative Methods, quoted in Nature 2006,440, 856 following the trial disaster)
Similar concerns about the value of animal tests are being made for chemicals. Animal tests are increasingly being seen as relatively uninformative; toxicologists look at the adverse effects on the animals or count how many that die. This doesn’t tell you very much about how and why the chemical had the effect it did. A new way forward has been proposed by the US National Academy of Sciences in their breakthrough report: Toxicity Testing in the Twenty-first Century: A Vision and a Strategy. They suggest a move away from animal testing towards understanding the toxicity pathways of chemicals.
Better alternatives
Animal experiments have been used for hundreds of years and it’s time to move on. In the 21st century we have technological options not available before – computer modelling, human cell and tissue cultures, microdosing, sophisticated imaging and analysis. Whenever and wherever resources are ploughed into developing non-animal techniques, quicker, more reliable and usually cheaper tests result. We need more money, time and resources devoted to this. For more information see Alternatives.
