If we don’t train our dogs properly they will not behave like they are supposed too! In this list You will see which are the most aggressive dogs, when not trained, or when they have been kept isolated from the world! It is not necessarily a dog that defines the whole breed. Anyways studies have shown that these 10 aggressive dogs have bitten a couple of people, just because they have felt threatened or scared! Remember dogs only bite for self-protection!
They have been used as police dogs, guards, or for protection. Therefore they were not expected to be friendly at first! Now that people use them as companions they have calmed down, and have bitten only nine people according to studies.