This review may contain spoilers. I can handle the truth.
This movie introduces a dog and makes multiple obvious hints throughout that it's going to be killed, only for it to survive the whole grim ordeal. The killer doesn't even try and kill it, not even when it's attacking him; he mostly ignores the dog while butchering its owners and even lets it leave with him, which ultimately leads to his capture by police. There's a lot to praise about this movie's overwhelming cinematic style and the way in which it explores its protagonist's mindset with such creepy intimacy, but I have to be honest: this movie is mainly a masterpiece because of the dog.