Love that picture P.Pete :))
They just dismiss animals as lesser lifeforms that don't really matter. The most egregious passage in the Bible is the one in Genesis that says man should have Dominion over the animals, birds and fishes. It's allowed for such harm.
But if the definition of a "person" is the capacity to suffer, practically all animals - and certainly vertebrates , no wait what about octopi? Nevermind make that all animals, are "persons".
JWs aren't much different from many humans in that sense. As a veggie I think It's the one true "ISM" there really is, species-ism.