n.
Operation on a living animal for experimental rather than healing purposes; more broadly, all experimentation on live animals.
It is opposed by many as cruelty and supported by others on the ground that it advances medicine; a middle position is to oppose unnecessarily cruel practices, use alternatives when possible, and restrict experiments to necessary medical research (as opposed, for example, to cosmetics testing). Surgery on animals without anesthesia was once common; many people, most significantly Rene Descartes , claimed that animals did not really feel pain. Testing chemicals on animals to find the lethal dose still occurs despite alternative methods (computer simulations, tissue culture tests). An antivivisection movement in the late 19th century broadened its scope to include prevention of all cruelty to animals and later gave rise to the animal rights movement.