According to Aristotle's classical model of persuasion, there are three appeals that can be used to persuade an audience: logos, ethos, and pathos.
Logos is appeal to logic, ethos to ethics, pathos to emotions. Pathos usually focuses on sad emotions, or emotions related to pity, in order to persuade. That is precisely what Abby is doing when she tells the story of the pain and torment an animal went through. She is appealing to the audience's capacity for empathy, for feeling the animal's pain, for feeling sorry for the animal. She expects their emotions will persuade them to stop animal testing.
