Why should animals not be used in research?

The thing is that it's called "cruelty to animals"

Why?

1. Some animals are killed because it doesn't work or it's poisonous to that kind of animal.

2. They can be seriously hurt or messed up because people put in the wrong chemicals and a little experimenting would fix the formula.

3. It's done against their will.

Animals are as important as you are and deserve to have a just life.