This Is How Many Animals Are Used In Medical Experiments In Britain

Lots of mice, basically.

The Home Office has just released statistics showing how many animals were used in medical experiments in 2014.

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Essentially, it's all mice. Of the total of 3,867,439 procedures, nearly 3 million were on mice; another 250,000 were on rats.

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A few provisos: The stats don't include insects and other invertebrates (apart from squid and octopuses), and they don't include embryos. They do, for the first time, include things like tadpoles, which were previously classed as embryos.

Fewer than 5,000 procedures were carried out on primates.

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Hamsters had a bad year, though: While there were just 2,750 procedures carried out on them, that represents almost a 50% increase from the year before.

The majority of animals weren't actually "experimented on" in the way we might think of it. They were bred with genetic changes, but not subjected to any other experiments.

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Of the 1.94 million animals bred (91% of which were mice), 54% had some sort of negative impact from their modifications. Only 2% were classified as "severe" impacts, though, while 4% were "moderate".

Most of the procedures were for "basic research": that is, finding out how the body works, or how diseases progress.

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Almost all the rest is either applied research – testing cures or treatments for specific diseases – or regulation (testing whether a drug or other product meets safety standards).

The bulk of the animals bred for basic research are used to gain information about our immune systems and nervous systems, and to learn how cancers develop.

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Most applied research procedures are trying to find treatments for cancers and infectious diseases.

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The number of experimental procedures has stopped increasing.

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The total number of animals tested on has been going up, but that trend appears to be slowing or reversing. Further, most of the rise has come from an increase in the number of animals bred with genetic modification; the number of animals being used in actual experiments has remained roughly steady since 2009.

The most recent data shows a drop in both experiments and breeding, but the Home Office warns that its data collection methods have changed, so this may not be accurate. We've represented it in a different colour on the chart to mark it as separate.