Ibn al-Nafis provided accurate descriptions of the circulation of blood in mammals. A complete description of this circulation was later provided in the 17th century by William Harvey.
The physicist, Robert Boyle conducted many experiments with a pump to investigate the effects of rarefied air. He listed two experiments on living animals: "Experiment 40", which tested the ability of insects to fly under reduced air pressure, and the dramatic "Experiment 41," which demonstrated the reliance of living creatures on the air for their survival.
Antoine Lavoisier decided to use a guinea pig in a calorimeter because he wanted to prove that respiration was a form of combustion. He had an impression that combustion and respiration are chemically identical. Lavoisier demonstrated this with the help of Pierre-Simon Laplace.
Luigi Galvani demonstrated that electricity applied to a dead, dissected, frog's leg muscle caused it to twitch, which led to an appreciation for the relationship between electricity and animation.
Louis Pasteur convincingly demonstrated the germ theory of medicine by giving anthrax to sheep. In the 1890s, Ivan Pavlov famously used dogs to describe classical conditioning.
Otto Loewi provided the first substantial evidence that neuronal communication with target cells occurred via chemical synapses. He extracted two hearts from frogs and left them beating in an ionic bath.
David Hubel and Torsten Wiesel demonstrated the macro columnar organization of visual areas in cats and monkeys, and provided physiological evidence for the critical period for the development of disparity sensitivity in vision (i.e.: the main cue for depth perception), and were awarded a Nobel Prize for their work.
Dolly the sheep was born, the first mammal to be cloned from an adult cell. The process by which Dolly the sheep was cloned utilized a process known as nuclear transfer applied by lead scientist Ian Wilmut.
Innovations in frogs, Xenopus laevis, by developmental biologist Jonathan Slack of the University of Bath, created headless tadpoles, which could allow future applications in donor organ transplantation.