There isn't anything on an animal that can be used to determine whether or not it's wild or domestic. The only determining factor of whether or not an animal is wild or not is where it lives.

Simply put, domestic animals live with human beings while wild animals live in the wild. The claws of a domesticated animals may be clipped every once in a while by its owner but that doesn't differentiate it from wild animals, people have poisonous fishes as pets and those same fishes can be found in the wild. The only way to know if an animal is wild or not is to check where it stays.