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These bunny rabbits are the forgotten heroes of World War II

Bunnies hard at work testing penicillin in 1946, at a facility in Speke, Liverpool.
Bunnies hard at work testing penicillin in 1946, at a facility in Speke, Liverpool.
Getty

World War II involved contributions from nearly all Americans, but there's one forgotten group that helped save millions of lives: bunny rabbits.

During the 1940s — and especially during World War II — penicillin was an increasingly popular wonder drug. High demand for penicillin meant scientists had to figure out how to produce — and test — large new batches as quickly as possible. And, like many groups around the world, the team in Terre Haute, Indiana found that testing on rabbits worked best.

They used New Zealand white rabbits, which are actually most common in the United States. Technicians would inject penicillin in a vein in each rabbit's ear and observe if the animal's temperature showed signs of fever. If it did, the batch was thrown out.

Bunny being weighed

A bunny being weighed in the same Liverpool facility. (Getty)

The rabbit pyrogen test is no doubt familiar to modern researchers, since it's still in use today (though alternatives are also used). But during the 1940s, the test had urgency, utility, and novelty, when a few bunnies were the only workable way to ensure that penicillin was safe to ship. Pioneered in the 1920s by Florence Seibert, the first official rabbit test in 1942 offered researchers a way to test large quantities quickly. The technique quickly spread around the world (it was so popular that one of the biggest risks was a rabbit shortage, which actually happened in Germany).