Justifications for invasive experiments on animals rely on claims that such research is essential for the advancement of biomedical knowledge, for the development of cures to human diseases, or for the evaluation of the toxicity of compounds to which humans are exposed. Until recently, critical evaluations of the accuracy of such claims have been rare. However, a growing body of large-scale systematic reviews have now been published in scientific and medical journals. The outcomes have been consistent: animal experiments have contributed far less than advocates would have us believe. This presentation summarises these recent results, and comprehensively reviews the alternatives to invasive animal use with biomedical research, toxicity testing, and education. Published studies are available at www.AnimalExperiments.info.

1. THE COSTS AND BENEFITS O F
ANIMAL EXPERIMENTS
Andrew Knight
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THECOSTSANDBENEFITSOFANIMALEXPERIMENTS
AndrewKnight
Animal Experiments
and Alternatives
ANDREW KNIGHTANDREW KNIGHT
DipECAWBM (AWSEL), DACAW,DipECAWBM (AWSEL), DACAW,
PhD, MANZCVS, MRCVS, SFHEAPhD, MANZCVS, MRCVS, SFHEA

2. Scientific resistance to alternatives
Non-compliance of US researchers with the alternatives
regulations of the Animal Welfare Act:
 Most common: inadequate consideration of alternatives
(600 - 800 research facilities).
 Fourth most common: unnecessary experimental
duplication (~ 250 facilities).
 Others: inadequate justification for animal numbers,
alleged uncertainty of research personnel about signs
indicative of pain and/or distress (USDA-APHIS-AC,
2000).

3.  Chemical companies submitting test plans often failed to follow minimal
EPA guidance about 3Rs alternatives:
 failed to use existing published data
 failed to avoid duplicative or otherwise unnecessary animal testing
 proposed irrelevant or unnecessary tests (such as acute fish toxicity
tests on water-insoluble chemicals)
 Ignored opportunities to use non-animal tests
 failed to utilise opportunities to combine protocols, sometimes
doubling the number of animals killed
 In its responses to test plan proposals, the EPA frequently failed to
encourage companies to follow basic animal welfare principles (Sandusky
et al., 2006).
High Production Volume (HPV)
test program

4. Scientific support for
animal experimentation
 Animal experimentation is vital for preventing, curing or
alleviating human diseases (e.g. Brom 2002, Festing 2004).
 The greatest achievements of medicine have been possible
only due to the use of animals (e.g. Pawlik 1998).
 The complexity of humans requires nothing less than the
complexity of laboratory animals to effectively model during
biomedical investigations (e.g. Kjellmer 2002).
 Medical progress would be “severely maimed by prohibition
or severe curtailing of animal experiments,” and
“catastrophic consequences would ensue” (Osswald 1992).

5. Concordance or discordance?
Drugs causing serious side effects or death in some
laboratory animal species that are harmless to
humans:
 Penicillin
 Morphine
 Aspirin
 …

6. Drugs released onto the market after passing more rigorous
testing in animals, and very limited testing in humans, that
have caused serious human side effects:
 TGN1412 (UK, 2006)
 Vioxx
 Thalidomide, Eraldin, Chloramphenid, Ibufenac,
Flosint, Zipeprol, Zomax, Accutane, Benedectin,
Phenformin
 Many, many more…
Such adverse drug reactions have been recorded as the 4-6th
leading cause of death in US hospitals, and kill over
10,000 people annually in the UK.

7. Calls for systematic reviews
Clinicians and the public often consider it axiomatic that
animal research has contributed to human clinical knowledge,
on the basis of anecdotes or unsupported claims.
These constitute an inadequate form of evidence for such a
controversial area of research, particularly given increasing
competition for scarce research resources.
Hence, formal evaluation of existing and future animal
research is urgently required, e.g., via systematic reviews of
existing animal experiments.
- Pound et al. Brit Med J, 2004.

8. Systematic reviews:
‘gold standard’ evidence
 Critically examine human clinical or toxicological utility of
animal experiments
 Examine large numbers of experiments, usually sourced via
multiple bibliographic databases
 Any subsets of experiments must be selected without bias, via
randomisation or similarly methodical and impartial means
 Studies published in peer-reviewed biomedical journals

9. - Altern Lab Anim, 2007.
- Rev Recent Clin Trials, 2008.
- Palgrave Macmillan, 2011.

10. 27 systematic reviews of the utility of animal studies in
advancing human clinical outcomes (20), or in deriving human
toxicity classifications (7)
Three different approaches sought to determine the maximum
clinical utility that may be achieved by animal studies…

11. 1. Experiments expected to lead to
medical advances
Lindl et al. (2005 & 2006) examined animal experiments
conducted at three German universities between 1991 and
1993, that had been approved by animal ethics committees
partly on the basis of researcher claims that the experiments
might lead to concrete advances towards the cure of human
diseases.
For 17 experiments meeting the inclusion criteria, citations
were analysed for at least 12 years. 1,183 citations were
evident.
However …

12. Only 8.2% of all citations (97) were in clinical publications.
Of these, only 0.3% of all citations (4 publications)
demonstrated a direct correlation between the results of animal
experiments and human outcomes.
However, even in these four cases the hypotheses that had
been successfully verified in animals failed when applied to
humans.
None of these 17 experiments led to any new therapies, or
any beneficial clinical impact during the period studied.

13. 2. Clinical utility of
highly cited animal experiments
Animal studies with > 500 citations
Published in the 7 leading scientific journals when ranked by
journal impact factor
76 animal studies were located with a median citation count of
889 (range: 639 - 2,233)
However…

14. Only 36.8% (28/76) were replicated in human randomised
trials. 18.4% (14/76) were contradicted by randomised trials,
and 44.7% (34/76) had not translated to clinical trials
Ultimately, only 10.5% (8/76) of these medical interventions
were subsequently approved for use in patients
- Hackam & Redelmeier. J Am Med Assoc, 2006.

15. Even in these cases human benefit cannot be assumed,
because adverse reactions to approved interventions are
the 4th
- 6th
leading cause of death in US hospitals
- Lazarou & Pomeranz. J Am Med Assoc, 1998.

16. Translation rates of most animal
experiments are much lower
Most experiments are neither highly cited nor published in
leading journals. Many experiments are not published at all.
The selective focusing on positive animal data while ignoring
negative results (optimism bias) is one of several factors
identified that may have increased the likelihood of translation
beyond that scientifically warranted.
Rigorous meta-analysis of all relevant animal experimental
data would probably significantly decrease the translation
rate to clinical trials (Hackam, 2007).

17. Only 48.7% (37/76) of these highly cited animal studies
published in leading journals were of good methodological
quality
Common deficiences:
lack of random allocation of animals
blinded assessment of outcomes
- Hackam & Redelmeier. J Am Med Assoc, 2006.
Poor methodological quality

18. 3. Invasive chimpanzee research
Passionate calls for increased funding of such research, e.g.
VandeBerg et al. (Nature 2005):
Such research has been of critical importance during struggles
against major human diseases such as AIDS, hepatitis and cancer
The genetic similarities between humans and chimpanzees — our
closest living relatives — makes them ideal biomedical research
models

19. J Appl Amim Welf Sci, 2007 Philos, Ethics, Humanit Med, 2008

20. Contributions to biomedical knowledge
749 studies of captive chimpanzees or chimpanzee tissues,
from 1995-2004:
Figure 1: Chimpanzee experiments
1995-2004 (total 749)
48%
42%
3%
3%
2%
2%
Biology (363)
Diseases: virology (311)
Therapeutic
investigations (26)
Diseases: parasitology
(23)
Miscellaneous (14)
Diseases: other (12)

21. Figure 2: Biology experiments
(363 of 749)
37%
21%
10%
9%
7%
7%
6%
2%
1%
Cognition/Neuroanato
my/Neurology (133)
Behavior/Communicati
on (75)
Immunology (37)
Biochemistry (34)
Reproduction/Endocri
nology (27)
Genetics (25)
Anatomy/Histology (20)
Physiology (9)
Microbiology (3)

22. 21 others: Six: FV. Four: HAV. Two each: GBV – B,
HIV & HV, IV, PIV, Noroviuses. One each:
Bacteriophages, Dengue v., Ebola v., HCMV, HGV,
HMPV, H/S TLV, LCV, Papillomaviruses, RV2,
Rhinovirus, VZV, WMHBV, Unspecified.
Figure 3: Virology experiments
(311 of 749)
31%
31%
9%
4%
4%
3%
3%
2%
2%
11%
HCV (97)
HIV (97)
HBV (29)
RSV (12)
HEV (11)
STLV (9)
HIV & SIV (8)
SIV (7)
TTV (7)
21 others (34)
HCV = hepatitis C v., HIV = human immunodeficiency v., HBV = hepatitis B
v., RSV = respiratory syncytial v., HEV = hepatitis E v., STLV = simian T-cell
lymphotropic v., SIV = simian immunodeficiency v., TTV = transfusion-
transmitted v., FV = foamy v (human and simian FV), HAV = hepatitis A v.,
GBV-B = GB virus B, HV = herpes v., IV = influenza v., PIV = parainfluenza
v., HCMV = human cytomegalovirus, HGV = hepatitis G v., HMPV = human
metapneumovirus, H/S TLV = human/simian T-cell leukemia v., LCV =
lymphocryptoviruses, RV2 = rhadinovirus (or gamma-2-herpesvirus)
genogroup 2, VZV = varicella-zoster v., WMHBV = woolly monkey hepatitis
B v.

23. Remaining chimpanzee studies
pharmacological and toxicological studies of various
compounds
testing of surgical techniques or prostheses, and
anaesthesiology experiments
investigations of laboratory/husbandry techniques
radiation studies
various disease studies, including endotoxaemia and eight
parasitic species

24. Implications?
Research on captive chimpanzees or chimpanzee tissue
appears to have contributed towards a large array of
biomedical disciplines.
However, not all knowledge has significant value, nor is
worth the costs that may be incurred.

25. Figure 4: Citations of
95 randomly selected
published chimpanzee studies
47
34
14
0
10
20
30
40
50
Not subsequently
cited
Cited by other
paper
Cited by medical
paper

26. Citations by medical papers
63% (17/27) of these medical papers were wide-ranging reviews
of 26 - 300 (median 104) references, to which the cited
chimpanzee study made only a small contribution
No chimpanzee study demonstrated an essential
contribution, or ― in a clear majority of cases ― a
significant contribution of any kind, towards papers
describing well-developed prophylactic, diagnostic or
therapeutic methods for combating human diseases!

27. 27 systematic reviews:
overall results
The authors concluded that the animal models were useful in
advancing human clinical outcomes, or substantially
consistent with human outcomes, in only 2 of 20 studies, and
the conclusion in 1 case was contentious
7 reviews failed to demonstrate reliable predictivity of human
toxicological outcomes such as carcinogenicity and
teratogenicity
- Knight.- Knight. Altern Lab Anim,Altern Lab Anim, 2007.2007.
- Knight.- Knight. Rev Recent Clin Trials,Rev Recent Clin Trials, 2008.2008.

28. Causes: 1. Interspecies differences
 Altered susceptibility to and progression of diseases
 Differing absorption, tissue distribution, metabolism, and
excretion of pharmaceutical agents and toxins
 Differences in the toxicity and efficacy of pharmaceuticals

29.  Loss of biological variability or predictivity resulting from
the use of in-bred strains, young animals, restriction to
single genders, and inadequate group sizes.
 Lack of comorbidities (concurrent illnesses) or other human
risk factors.
 Physiological or immunological distortions resulting from
stressful environments and procedures.

30. 2. Stressful environments
and protocols
Most laboratory animals spend most of their lives in
small, relatively barren cages. A review of 110 studies
from the biomedical literature revealed the outcomes:
- Balcombe- Balcombe et al. Lab Animet al. Lab Anim 20062006
Impacts of laboratory housing

31.  Deleterious neuroanatomical, psychological (eg,
stereotypical behaviour) and physiological effects
 Distortion of many subsequent scientific results
 Even so-called ‘enriched’ environments fail to
ameliorate most of these deficits
- Balcombe- Balcombe et al. Lab Animet al. Lab Anim 20062006

32. Impacts of common procedures
All common laboratory species suffer marked stress,
fear and possibly distress (indicated by the distortion
of a broad range of physiological parameters) when
subjected to:
 Handling
 Blood sampling
 Gavaging (insertion of an esophageal tube for
the oral administration of test compounds — a
common procedure in toxicity studies)
- Balcombe- Balcombe et al. Contemporary Topics Lab Anim Sciet al. Contemporary Topics Lab Anim Sci 20042004

33. Animals do not readily habituate to these procedures
over time.
This stressful alteration of normal physiological
parameters also predisposes to a range of pathologies
and distorts scientific results.
- Balcombe- Balcombe et al. Contemporary Topics Lab Anim Sciet al. Contemporary Topics Lab Anim Sci 20042004

34. 3. False positive results of chronic
high dose rodent studies
 Overwhelming of natural physiological defences such as
epithelial shedding, inducible enzymes, DNA and tissue repair
mechanisms, which effectively protect against many naturally
occurring toxins at environmentally relevant levels
 Differences in rodent physiology when compared to humans,
e.g.: increased metabolic and decreased DNA excision repair
rates

35.  Unnatural elevation of cell division rates during ad libitum (‘at
will’) feeding studies
 Variable, yet substantial, stresses caused by handling and
restraint, and frequently stressful routes of administration, and
subsequent effects on hormonal regulation, immune status and
disease predisposition

36. 4. Poor methodological quality of
animal experiments
 At least 11 systematic reviews demonstrated the poor
methodological quality of many of the animal experiments
examined
 None demonstrated good methodological quality of a majority
of experiments

37. Common deficiences
Lack of:
sample size calculations
sufficient sample sizes
randomised treatment allocation
blinded drug administration
blinded induction of injury (ischaemia in the case of
stroke models)
blinded outcome assessment
conflict of interest statements

38. Conclusions
 Historical and contemporary paradigm:
 Animal models are fairly predictive of human outcomes.
 Provides the basis for their widespread use in toxicity testing and
biomedical research aimed at developing cures for human diseases.
 However, their use persists for historical and cultural reasons,
rather than because they have been demonstrated to be
scientifically valid.
 E.g., many regulatory officials “feel more comfortable” with animal
data (O’Connor 1997).
 Some even believe animal tests are inherently valid, simply because
they are conducted in animals (Balls 2004).

39.  However, most systematic reviews have demonstrated that
animal models are insufficiently predictive of human
outcomes to offer substantial benefit during the development
of clinical interventions, or during human toxicity
assessment.
 Consequently, animal data may not be generally assumed to
be useful for these purposes.

40. 3Rs alternatives
 Replacement
 Reduction
 Refinement
 (Recycling?)
 (Rehabilitation)

41. Replacement alternatives
Mechanisms to enhance sharing and assessment of
existing data, prior to conducting further studies.

42. Physicochemical evaluation and computerized modelling,
including the use of structure-activity relationships, and
expert systems.
Allow predictions about toxicity and related biological
outcomes, such as metabolic fate.

43. Minimally-sentient animals from lower phylogenetic
orders, or early developmental vertebral stages, as well as
microorganisms and higher plants.

44. A variety of tissue cultures, including immortalised cell
lines, embryonic and adult stem cells, and organotypic
cultures.

45.  In vitro assays (tests) utilising bacterial, yeast, protozoal,
mammalian or human cell cultures exist for a wide range of
toxic and other endpoints. These may be static, or perfused,
and used individually, or combined within test batteries.
 Human hepatocyte (liver cell) cultures and metabolic
activation systems offer potential assessment of metabolite
(a product of metabolism, usually by the liver) activity — a
very important consideration when assessing toxicity.

46. cDNA microarrays (‘gene chips’) allow assessment of large
numbers of genes simultaneously. This may allow genetic
expression profiling (detection of up- or down-regulation of
genes, caused by exposure to test compounds). This can
increase the speed of toxin detection, well prior to more
invasive endpoints.

47. The safety profile and predictivity for diverse human patient
populations of clinical trials should be improved using
microdosing, biomarkers, staggered dosing, more
representative test populations, and longer exposure periods

48.  Surrogate human tissues and advanced imaging modalities
 Human epidemiological, psychological and sociological
studies
 Particularly when human tissues are used, non-animal models
may generate faster, cheaper results, more reliably predictive
for humans, yielding greater insights into human
biochemical processes

49. Reduction alternatives
 Improvements in experimental design and statistical
analysis; particularly, adequate sample sizes.
 Minimising animal numbers without unacceptably
compromising statistical power, through decreasing data
variability:
 Environmental enrichment, aimed at decreasing physiological,
psychological or behavioural variation resulting from barren
laboratory housing and stressful procedures.
 Choosing, where possible, to measure variables with low inherent
variability.
 Genetically homogeneous (isogenic or inbred) or specified
pathogen-free animal strains.
 Screening raw data for obvious errors or outliers.

50.  Meta-analysis (aggregation and statistical analysis
of suitable data from multiple experiments). For
some purposes, treatment and control groups can be
combined, permitting group numbers to be
minimised.

51. Refinement alternatives
 Analgesics and anaesthetics. (Around 60% of UK
procedures are conducted without anaesthetics).
While such drugs undoubtedly alter normal physiology, claims that such
alterations are sufficiently important to hypotheses under investigation, to
warrant their exclusion, require careful scrutiny.

52.  Non-invasive imaging modalities.
 Telemetric devices to obtain information remotely.
 Faecal analysis (e.g. faecal cortisol monitoring).
 Training animals (especially primates) to participate (e.g.
presenting arms for blood-sampling), rather than using
physical or chemical restraint.
 Environmental enrichment.
 Socialisation opportunities.

53. Increasing 3Rs compliance
 Technology reproducibility and transfer: increased
methodology description, e.g., via publicly-accessible
databases, linked to scientific articles.
 Redirection of public funds from animal modelling to
alternatives development/implementation.

54.  Increased 3Rs compliance should be necessary for research
funding, ethics committee approval, and publication of results.
Would require education and cooperation of funding agencies,
ethics committees and journal editors about the limitations of
animal models, and the potential of alternatives.
 National centres for the development of alternative methods.
 Scientific recognition: awards, career options.

55.  Greater selection of test models more predictive of human
outcomes
 Increased safety of people exposed to chemicals that have
passed toxicity tests
 Increased efficiency during the development of human
pharmaceuticals and other therapeutic interventions
 Decreased wastage of animal, personnel and financial
resources.
Likely benefits

56. The scientific and logistical limitations incurred by the use of
animal models of humans within biomedical research and
toxicity testing are substantial, and increasingly recognized.
So is social concern about, and consequent regulatory
restriction of, laboratory animal use.
In defiance of these factors, such use remains enormous.
Increased use of GM animals, and the implementation of
large-scale chemical testing programs, are increasing
laboratory animal use internationally.
Conclusions

57. These trends clearly demonstrate the need for considerably
greater awareness of, and compliance with, the principles of
the 3Rs.
These principles are universally recognized as essential to
good laboratory animal practice, for animal welfare-related
and ethical reasons, and also, to increase the quality of the
research, and the robustness of subsequent results.

58. Policy reforms:
1. Animals protected
Regulatory protection should be based on current scientific
knowledge about:
neuroanatomical architecture
cognitive, psychological, and social characteristics
consequent capacity for suffering in laboratory environments
and protocols.

59. Sufficient scientific evidence exists to warrant the protection of:
all living vertebrates
advanced larval forms and foetal developmental stages
certain invertebrates such as cephalopods

60. Similar protection is warranted for:
animals used to develop or maintain GM strains
bred for organ or tissue harvesting
bred or intended for laboratory use, including those killed
when surplus to requirements

61. 2. Species and procedures
associated with high welfare risks
Primate sourcing and use
Terminal or surgical procedures
Major physiological challenges
The production of GM animals
Procedures resulting in pain, suffering, or distress likely to be
severe or long-lasting

62. 3. Scrutiny of animal use
Independent scientific and public scrutiny of proposed
protocols
Independent ethical review

63. Directive 2010/63/EU on the
protection of animals used for
scientific purposes
‘It is essential, both on moral and scientific grounds, to
ensure that each use of an animal is carefully evaluated as
to the scientific or educational validity, usefulness and
relevance of the expected result of that use.’
‘The likely harm to the animal should be balanced
against the expected benefits of the project.’

64. Thorough searches for replacement, reduction, and refinement
methodologies
Where scientifically suitable alternatives are identified, they
should be used

65. 4. Retrospective evaluation
To assess the degree to which experimental objectives were
successfully met
The extent to which animals suffered
To inform future research strategy
Future experimental licensing decisions
Minimise unwarranted experimental duplication

66. Cited studies:
www.AnimalExperiments.info
Thank you
for your attention!
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