First, find your common ground quickly by explaining that you do not believe in animal cruelty. No living, pain-capable creature should be subjected to inhumane treatment. But you have to quickly get down to showing them the logical conclusion of what they are saying.  

Tim Brahm from Equal Rights Institute has also noticed this trend. He says, “People don’t like losing arguments, and often people will basically offer to bite that bullet to try to get around the conclusion of the Equal Rights Argument (that the preborn have the same rights as the born). Our initial response might be to do something like to trot out a toddler and ask, “What if someone shot a squirrel right here, and then shot a two-year-old human? Would those be equally wrong?” While oftentimes people see the problem and shift, sometimes they just bite the bullet and say, “Yep, those are equally wrong.”” So, how should you respond?  

Tim suggests that there is an ambiguity in the word “wrong,” which, if it doesn’t get clarified, very easily allows the pro-choice advocate to get away with biting a less painful bullet than the one they really should have to bite. That ambiguity is the difference between something being morally wrong and legally punishable. It’s easy to say, “My personal judgment is that they are both equally morally wrong,” and hard to say, “I advocate we adjust the law accordingly.” Equal Rights Institute started using the following response, the Hunting Story, to clarify this ambiguity, and it has been incredibly successful.

• “I have a friend named Jacob. He’s a self-proclaimed redneck from Texas and a couple of years ago, he went hunting. He stalked a deer, shot and killed it, skinned it, chopped it up, made sausage out of it, and then we ate it.  The question is not, “Was what Jacob did evil?” The question is, “What should his punishment be?” What if he had done the same thing to, say, a ten-year-old girl? What if he stalked her, shot and killed her, skinned her, chopped her up, made sausage out of her, and then ate her? Should the punishment be the same for both of those crimes? If not, why not?” 

The semi-formal name for the technique is called “Taking the Roof Off” the argument. Their position may not have any logical flaws or blatant contradictions, so instead you simply drive their argument to its logical conclusion to show how absurd it is. The idea is to just demonstrate how extreme and “explosive” the implications are that it blows up and “takes the roof off”.  So, for people who say killing a frog is the same as killing a toddler, you want to challenge them to accept the implications. If they stick to their guns, there isn’t much you can do besides offer a more reasonable alternative, but you can expose their craziness to everyone else listening.