Research agencies have ordered UK scientists to improve the way they use animals in experiments. Too often poorly designed projects – to test new medicines for strokes, cancer and other conditions – have produced meaningless results and wasted animals’ lives, the organisations have warned.

In some cases, researchers – desperate to control the costs of their work – have underestimated the number of animals needed to test a new medicine. As a result, their tiny studies have lacked the power to pinpoint biological effects in the drugs under scrutiny. These unreliable results mean the lives of the animals involved have been wasted, along with scientists’ time and resources. The over-use of animals in experiments has also led to unnecessary loss of their lives.

The problem of poorly designed studies has been under investigation for two years and culminated, last week, in Research Councils UK – the umbrella group for the councils that fund UK research – announcing changes to its guidelines for those carrying out research using animals. Scientists will now have to show their work will not only produce physiological insights but will also generate statistically robust data. If not, they will lose their funding.

“There has been an increasing awareness that some animal experiments are not sufficiently robust. These guidelines should therefore be welcomed, although they have taken a long time to be introduced,” said neuroscientist Malcolm Macleod of Edinburgh University.

In 2013, 4.12 million scientific procedures on animals – mostly rats and mice – were started in Great Britain. Half involved breeding genetically modified animals. The other half involved experiments on unmodified animals, of which 58% were carried out for fundamental research, 26% for human medicine and 8% for veterinary purposes.

Many of these are done to test drugs before human trials are launched. However, it takes a fairly large number of animals to reveal whether a drug is having a pharmacological effect, said Macleod. “In a typical £300,000 project – say to test a stroke drug – about a third of funds goes on equipment, a third on salaries and a third on animals. To keep costs down – and there is constant pressure to do so by agencies – you might try to limit numbers of animals. But that means the power of your research to pinpoint a real biological effect is limited. Often your results are produced purely by chance. However, to make your research more robust – to raise its statistical power from 50% to 80% – you would have to double the number of animals you use and so increase its cost, in our example, by another £100,000.”

The problem of poorly designed experiments was identified in a recent survey of scientific papers which showed details of design and statistical analysis were sometimes inadequate, said immunologist Professor Paul Kaye of York University. “The new guidance will allow scientists to demonstrate to funders they have a full understanding of the issues involved in designing and analysing complex experiments involving animals.”

Mark Prescott, head of research policy for the UK National Centre for the Replacement, Refinement and Reduction of Animals in Research, said the guidelines represented a change for the scientific community. “Yes, you can use animals in experiments, but no more than necessary – and no fewer. It is ethically questionable to get the numbers wrong either way.”

Wendy Jarrett, chief executive of Understanding Animal Research, said: “The scientific community needs to use the latest data in order to make sure studies are appropriately powered. In some cases, this means fewer animals can be used, but sometimes it will lead to more being used in order to ensure we get meaningful results.”

This point was stressed by Penny Hawkins of the RSPCA. “It is good that this problem has been put right but bad that it took so long to do so. Animals have suffered unnecessarily and patients have been let down because public money has been wasted on worthless research. We now need to see how robustly the agencies follow up these new guidelines and ensure scientists comply with them.”