Dogs with six toes on their paws have a condition called polydactyly. This is a genetic anomaly that causes additional toes to form. Polydactyl dogs aren't very common, but some breeds, such as the Great Pyrenees, Newfoundland, and some other working or mountain dog breeds, may occasionally display this trait. In some cases, having extra toes can be an advantage, providing better stability and dexterity, especially in certain terrains or working conditions.