It is not always a clear picture. The term “aggression” refers to a wide variety of behaviors that occur for various reasons in various circumstances.
It’s intuitively clear to most owners that a dog who approaches aggressively, lunges, and bites is much more dangerous than one who hides, cowers, and snaps only when cornered. How much damage the dog causes or can cause when he bites, a dog who bites hard and causes serious injuries every time is a more significant risk than one with good bite inhibition and causes no puncture wounds or bruising during a bite.
Levels of Bites According to Ian Dunbar’s Scale of Bites
Level 1: aggressive but no skin contact.
Level 2: teeth make contact but do not break the skin.
Level 3: a single bite with shallow wounds.
Level 4: a single bite with deep wounds.
Level 5: multiple bites with deep wounds.
Level 6: death of the victim and/or flesh consumed.