There are a couple of explanations of why dogs howl at sirens, although not all dogs do. Some people think that due to the dog's sensitive hearing, the sirens hurt their ears and they are howling in pain. According to the American Kennel Club, however, this is not true. Dogs aren't the only animals that howl. Wolves and coyotes howl as well, and while it often sounds very lonely, it is a form of communication. They have a keen sense of hearing, and a howl can be heard a long way away. A wolf who howls may be saying ",Hey! Where are you guys?", and the pack answers back with ",We're over here!", When dogs howl at sirens, they may be expressing this instinctual behavior too. Some sirens may sound like the faraway howl of a dog, at least to another dog, and the dog may be offering up it's own howl in a helpful reply.