There is plenty of documented information about how animals suffer in circuses and why experiments on animals are not only cruel but dangerous, as results from one species can’t be accurately transferred to another (see Circuses.com and StopAnimalTests.com for cited fact sheets). Still, most people don’t need an encyclopedia entry to understand that beating and chaining animals for our “entertainment” or cutting them open and pumping them full of toxic substances simply because we can overpower them is wrong.
Animals aren’t so different from us: They think, feel pain and have an interest in living their own lives. Animal-free entertainment and alternatives to animal testing exist, so why continue causing animals terrible suffering?