"No animals were harmed during the making of this film" is a post-movie credit that everyone is familiar with. It puts animal lovers at ease to know that no creatures suffered unnecessarily for the sake of a movie. Of course, not everyone is as sympathetic. Some might argue that for the sake of authenticity, animal distress may be necessary. But this is never the case. Just take a look at Amores Perros. Alejandro Gonzalez Iñárritu's Mexican masterpiece contained some of the most brutal sequences of animal violence ever caught on camera, with rabid dogs appearing to tear one another limb from limb in stunningly realistic fashion. This naturally invited scrutiny from censorship boards and animal rights campaigners, but the film eventually passed uncut in the UK. Iñárritu went out of his way to ensure the safety of the animals, hiring expert trainers, placing muzzles on the dogs to prevent them hurting one another (or anyone else), and using particular editing and lighting to create the allusion of fierce animal violence. The dog-fighting has a specific purpose in Amores Perros: with the snarling canines symbolizing the animalistic nature of the Mexican people. It was important to Iñárritu that these scenes remained in the film, and he made sure all the necessary procedures were taken; making the violence appear authentic when it was anything but. The films on this list were not so careful or caring. These productions got themselves into all kinds of bother with the American Humane Association (AHA) and animal rights groups after revelations surfaced that animal cruelty, neglect, and even death had occurred during filmmaking. As you might expect, some of the accounts coming up are either pretty grim or just downright shocking. Get a hold of that gag reflex.