From NPR, the story of a mouse, and the verse written in its voice:
The year is 1773, and Joseph Priestley is busy working with "airs" (you or I would probably call them "gases"); his experiments were published beginning in 1774, and include the discovery of nitrous oxide, ammonia, and "dephlogisticated air" (we would call it "oxygen"; we can't quite credit him with discovering oxygen, for two reasons--first, others can legitimately make the claim, and second, he insisted on the phlogiston world-view). Priestley apparently went through quite a lot of mice in his experiments; in additioning to researching airs, he also examined lungs. Mice, in one experiment, were put in a chamber from which the oxygen would be removed; as you might expect, this did not end well for the mice.
Priestley's assistant, Anna Barbauld, wrote a bit of verse and (by the NPR account) left it in the cage of a mouse scheduled for the following morning's experiment. You can read the verse, or hear the whole story (in what I found to be a rather twitch-inducing edit) here at NPR's site. They quote historian Richard Holmes, who calls it "perhaps the first animal-rights manifesto ever written". I suspect a bit of revisionist history--we've had pet rodents, and I know how quickly they turn paper products into fluffy bedding. But the verse was published, so parts of the story ring true.
And, given the immense power of verse (something your pal Cuttlefish knows something about), from that moment onward, mice have been spared from participating in science.
Ok, it's still a cute little verse, a tear-jerker of a story, and some really cute watercolor illustrations.