People cannot live in laboratories for the long time it takes to conduct some experiments. More importantly, many scientific procedures and new medications cannot be given to humans until tests with laboratory animals have been done.
Many scientists love animals and have pets of their own.
They want to be sure their laboratory animals are as safe and comfortable as possible. Scientists want and need their animals to be healthy and safe. They do not want them to feel unnecessary pain. Also, unhealthy animals can jeopardize a research project. There are special guidelines that scientists must follow to be sure that their lab animals are safe.