There is currently a vehement debate in the Italian media about animal rights activism and experimentation on animals.

Caterina S., a person with four genetic diseases, publicly demonstrated her support for animal experimentation by stating that she was alive only thanks to it.

Valentina S.'s statement source

She was subsequently answered with death threats from (supposed) animal rights activists.

This induced a media frenzy. More than one biologist stated that animal experimentation is not only a useless cruelty, but also bad for research, and that it can be substituted by other means of experimentation. In particular Dr. Penco advocates using donated organs as test subjects:

Grazie alle mie conoscenze scientifiche [...] sono persuasa che, anche per le malattie più agghiaccianti, ossia delle quali non si conoscono le cause e che riducono fortemente la qualità della vita, sia proprio la sperimentazioni sugli animali ad allontanare le soluzioni e la guarigione per i malati.


Thanks to my scientific knowledge [...] I am convinced that, even for the most frightening diseases, that of which you do not know the causes and that greatly reduces the quality of life, it is precisely animal testing that makes it more difficult to find solutions and healing sick people.

Is this true? Does animal experimentation delay results in medical research?

  • 1
    Seems to be an international phenomenon, at least one major German news paper (the “Zeit”) had a full-page vitriol filled pamphlet just before Christmas on this topic. Dec 29, 2013 at 15:24
  • Is there some more context to this statement? I assume that it refers to the rather common argument that you could replace animals with cell cultures and that many animal models are not representative of human biology.
    – Mad Scientist
    Dec 29, 2013 at 15:30
  • @Fabian she advocates the use of donated organs and complains that animals give false results. She also says that the future is personalized medicine. She doesn't make much sense to me.
    – Sklivvz
    Dec 29, 2013 at 15:34
  • Skipping animal models would certainly be faster ... but presumable would see more adverse reactions during the early phases of human trials. I mean, even if you find yourself willing to sign-up for a first stage human trial (basic safety) under the current system (where the active ingredient will be known not be highly toxic in a couple of different animals) how would you feel about being the (heh!) guinea pig for something that has only been tested in vitro? Dec 29, 2013 at 20:05
  • @dmckee it wouldn't be faster at all since a hell of a lot of more molecules would need to be tested in the longer, more complicated and expensive human trials. Animal trials have also a usage to choose the best candidates to test further (not only to remove the worst ones) since the time and resources dedicated to human trials are necessarily limited.
    – Sklivvz
    Dec 29, 2013 at 20:12

1 Answer 1


There is a serious debate about how good animal models are in predicting the effect of new drugs on humans. This is a very complicated issue, and the answer is very likely to be completely different for different animal models.

There are indications that some animal models that were widely used turned out to be almost useless. One example is shown in the paper "Genomic responses in mouse models poorly mimic human inflammatory diseases" published in PNAS (see also the blog post from Derek Lowe on this paper):

Here, we show that, although acute inflammatory stresses from different etiologies result in highly similar genomic responses in humans, the responses in corresponding mouse models correlate poorly with the human conditions and also, one another.

Another paper examining multiple animal models is "Comparison of treatment effects between animal experiments and clinical trials: systematic review" published in BMJ:

Conclusions Discordance between animal and human studies may be due to bias or to the failure of animal models to mimic clinical disease adequately.

There are multiple reasons why animal studies would fail to correctly predict the result of specific drug candidates in humans. There could be fundamental differences in the biology between e.g. mice and humans in the specific parts affected by the disease and the drug candidate. But there are also some indications that the problem is in part due to flaws in the animal studies themselves. The paper "Can Animal Models of Disease Reliably Inform Human Studies?" published in PLOS Medicine states:

  • The value of animal experiments for predicting the effectiveness of treatment strategies in clinical trials has remained controversial, mainly because of a recurrent failure of interventions apparently promising in animal models to translate to the clinic.

  • Translational failure may be explained in part by methodological flaws in animal studies, leading to systematic bias and thereby to inadequate data and incorrect conclusions about efficacy.

  • Failures also result because of critical disparities, usually disease specific, between the animal models and the clinical trials testing the treatment strategy.

Systematic flaws in animal studies and issues like publication bias are something that can be changed, they are not an unavoidable issue. Cases where the biology is too different between the laboratory animals and humans are much more difficult.

The fundamental issue is that we just don't have anything better available than animal experiments in most cases. Studies in humans have to meet very high ethical barriers. And in vitro experiments and cell cultures are much, much farther away from the actual human biology than even the flawed animal models. Derek Lowe writes about animal experiments from the perspective of a chemist in the pharmaceutical industry::

So that's my answer: we use animals because we have (as yet) no alternative. And our animal assays prove that to us over and over by surprising us with things we didn't know, and that we would have had no other opportunity to learn. We'd very much like to be able to do things differently, since "differently" would surely mean "faster and more cheaply". None of us enjoy it when our compounds sicken healthy animals, or have no effect on sick ones. Just the wasted time and effort alone is enough to make any drug discoverer think so. There are billions of dollars waiting to be picked up by anyone who finds a better way.

Animal models are certainly problematic in many cases, but they are still the best we have. There are no real alternatives in most cases.

  • "And in vitro experiments and cell cultures are much, much farther away from the actual human biology than even the bad animal models. " - this seems to be central to answering OP, but doesn't seem to be cited? Is that from Derek Lowe?
    – user5341
    Dec 30, 2013 at 2:21
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    Thats from me, though Derek Lowe certainly also wrote very similar statements. This is pretty much a basic principle in biological research, an in vitro experiment can't fully reproduce physiological conditions, and cell cultures are not full organs and can't reproduce their function. One argument I find convincing is that due to the high cost of animal experiments, the pharmaceutical industry would likely have abolished them if they could get away with it. There are efforts to replace specific animal experiments, so this will likely change over time.
    – Mad Scientist
    Dec 30, 2013 at 14:55
  • while I don't dispite that you're right, IMHO a cite for that principle still seems to be warranted, eh?
    – user5341
    Dec 30, 2013 at 15:08
  • Thanks for the detailed answer. What I am missing are good sources for two claims: The explicit claim that animal trials are better than the alternatives (the source you cite is a blog post), and the implicit claim that they are better than nothing. At the moment, you have the better sources doubting the use of animal models :)
    – P_S
    Jul 12, 2014 at 7:22

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