Dogs are by default (after the clearing of larger or more dangerous predators) the most powerful predators other than humans in many parts of the world. They remain cunning, swift, agile, strong, territorial, and voracious despite domestication; even small ones have large, sharp teeth and claws and powerful muscles in their jaws and legs, and can inflict serious injuries. The lacerations even from inadvertent dog scratches, let alone deliberate or reckless bites, are easily infected. Large dogs can knock people down. To be sure, dogs are far more reliable than other predators of like size (for example, leopards and cougars smaller than some breeds of dogs) and most larger herbivores. Dogs and humans are usually clever enough to recognize the folly of potential threats to each other and avoid danger, recognizing humans as themselves similarly predatory, or have mutual affection that precludes attack.

Should affection or mutual respect not exist (as with feral dogs), should a dog be conditioned to become an attacker, or should someone intrude upon a dog's territory and pose a threat, then the natural tendencies of a predator manifest themselves in a dog attack in which the dog, like all other formidable predators, uses its predatory abilities to defend itself. Usually a dog will attack some one if they threaten it or it's owner some times it's what the owner has trained the dog to do so it is usually not the dog's fault.