What are some cons on animal testing?

In animal testing, countless animals are experimented on and then killed after their use. Others are injured and will live the remainder of their lives in captivity. The unfortunate aspect is that many of these animals received tests for substances that will never actually be approved or used by the public. This aspect shows the idea that the animals die in vain because no direct benefit to humans occurred from this testing. There's also an argument that the reaction of a drug in an animal's body has quite a different reaction from the reaction in a human's.