We don't necessarily have to draw that line right now, we're talking about lice. Also, there is no way that dolphins are incapable of emotions, when my dog is capable of emotions. I know there's some disagreement on that subject.. but I see him displaying, let's call it "relatable behaviors", all the time. I didn't give him a treat, he got disappointed.. that sort of thing.

Empathy is essentially feeling the emotions of others, they need to have emotions in the first place.