Published online 25 March 2009 | Nature 458, 394-395 (2009) | doi:10.1038/458394a

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More pain studies needed

Scientists struggle to fund work on animal pain and distress.

J. MCDONALD/CORBIS

More research is needed on how to determine when a laboratory animal is in pain and how best to alleviate that pain, says a report from the US National Research Council. That conclusion may sound familiar; a report last year called for more research into laboratory animal distress, and a 1992 study said that more work was needed on pain and distress.

However, little has been done because the root problem — lack of money for such studies — has remained for decades. "Unless or until someone comes forward with the funding, it is not going to happen," says Gerald Gebhart, a pain researcher at the University of Pittsburgh in Pennsylvania and chairman of the committee that put together the new report.

Research into animal pain tends to fall between the purviews of existing funding agencies, the biggest of which typically have human health as their goal. "All of what we know today about pain in animals — well, 95% of it — comes from research on animals as models for human pain," says Andrew Rowan, a vice-president at the Humane Society of the United States, in Washington DC. For example, information on which pain medication regime is ideal for a mouse that has just had abdominal surgery might be gleaned from an experiment focused on what pain regime is ideal for humans.

In the United States, grants solely to study animal pain are rare and small. The funding situation is better across the Atlantic Ocean. "In Europe there is a lot of interest," says Vera Rogiers, head of the European Consensus Platform on 3R Alternatives, a non-profit organization based in Brussels. A proposal released late last year would tighten up a European Commission directive on the care of laboratory animals (see 'Europe to revise animal-testing rules'), which, among other things, would virtually ban studies on great apes, consider the pain of invertebrate species as well as vertebrates and enshrine the desirability of the three Rs: refinement, reduction and replacement.

“Pain research hasn't worked well because our animal models are inappropriate.”


Paul Flecknell, an author of the US report at the University of Newcastle, UK, has had grants from the Wellcome Trust in London, and the UK Biotechnology and Biological Sciences Research Council, among others, to maintain his studies on behavioural clues to animal pain and distress (A. L. Dickinson, M. C. Leach and P. A. Flecknell Lab. Anim. 43, 11–16; 2009). Still, he says, money is in "very short supply" for studies in which the primary goal is to improve practices in the use of lab animals. Some of his colleagues in other countries have cobbled together funding from veterinary charities and pharmaceutical companies for work on dogs and cats, and from agricultural agencies interested in poultry production for work on birds.

Animal-welfare organizations tend not to fund such research, as they focus on developing alternatives to animal research instead of refining current laboratory practices. And virtually no one funds research on pain and distress in the non-mammal vertebrates, such as fish, or the invertebrate worms commonly used in neurology studies.

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Supporting such research might one day have pay-offs for people. "Some of us in the pain field think that if one thinks that pain research hasn't worked particularly well — there are no new drugs in the clinic, really — that our animal models are inappropriate," says Jeffrey Mogil, a pain specialist at McGill University in Montreal, Canada.

Researchers who study human pain use animal models measuring how sensitive an animal is to touch after a painful stimulus. This 'mechanical allodynia' measures tenderness such as the pain evoked when a bruise is touched. But it does not measure 'spontaneous pain', such as the dull throb of a bruise that is not being touched. A better model of that in animals, says Mogil, could mean better treatments one day for pain in humans. 

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