Question

Is this a good hook for an introduction about animal testing? (I'm against it)

"Every year, millions of animals suffer and die in the U.S. from being tested for human products and medical treatments."

Answer 1

I would write, "Each ear, innumerable animals suffer and die at the hands of humans for testing various products and medical treatments." It's a similar variation of what you wrote. Go with what you feel fits the theme you are trying to portray.

Answer 2

this is a good hook because it provides a surprising fact and introduces the topic of the writing.