Charles Patterson's 2002 book Eternal Treblinka is a forcefully and even elegantly written denunciation of killing or harming animals, in the context of a history of slaughterhouses and of 20th century militant vegetarianism. It takes its title from a phrase in a story by Isaac Bashevis Singer, "The Letter Writer": "In relation to [all other creatures], all people are Nazis; for the animals it is an eternal Treblinka."
The book has forced me to think through my own position. I recognize the logic and respect the commitment in Patterson's book, but I'm not ready to become a vegetarian. There is a fundamental difference, in my mind, between genocide and animal slaughter, between killing human beings to rid the earth of them and killing beasts to provide for human beings. Where animal slaughter is a kind of genocide is in the deliberate exterminations of whole species, as nearly happened to the American bison and did happen to the dodo, the thylacine and many other animals -- all of which I regard as terrible errors, but not crimes comparable to what occurred at Treblinka, Auschwitz and other Lager (or in Cambodia or Rwanda or Darfur more recently). I'll focus my rage and what energy I can summon to defending humans first. But read the book. You may come to a different conclusion. In either case, you will be required to think through these issues more clearly.