'Conclusion: The contribution of animal studies to clinical medicine requires urgent formal evaluation. Systematic reviews and meta-analyses of the existing animal experiments
would represent an important step forward in this
process. Systematic reviews (particularly cumulative
meta-analyses of ongoing experiments22) could more
efficiently determine when a valid conclusion has been
reached from the animal studies. The UK Medical
Research Council requires researchers who are
planning clinical trials to reference systematic reviews
of previous related work.23 A requirement to reference,
or where necessary conduct, systematic reviews of
relevant animal studies before clinical trials would
make it difficult to disregard or selectively cite the evidence
from animal studies, or for animal and human
trials to proceed simultaneously.
By ensuring that animal experiments do not set out
to answer questions that have already been answered,
systematic reviews support the principle of reduction.
This principle, outlined in the “three Rs,” (reduction
and replacement of animals and refinement of procedures),
is held to be a cornerstone of animal research.24
Systematic reviews would also be relevant in veterinary
medicine to evaluate the efficacy of treatments for sick
animals.
Systematic reviews of animal research would
increase the precision of estimated treatment effects
used in calculating the power of proposed human
trials, reducing risk of false negative results. They are
able to throw light on the process of translation (or its
lack) between animal and clinical research as well
offering the opportunity to review the appropriateness
of the animal models used. Finally, the results of the
animal and human research need to be compared to
see how well one predicts the other.'

Pound P et al, Where is the evidence that animal research benefits humans? BMJ 2004