It's unusual for a dog to attack its owner, but it does happen every once in a while. It's rarely unprovoked and tends to occur for several reasons, including: 1. Instinct: If a dog is in a heightened state from chasing a squirrel or other animal and the owner comes out to grab their collar, they may attack from instinct, not thinking about hurting their owner. 2. Guarding Territory: Dogs are highly territorial creatures and may take a swipe at you if you reach out to grab a guarded toy or food item. It becomes more common if a dog is already highly stimulated by company or other activities. 3. Stress: Stress such as guests, weather, or fireworks can cause dogs to act out of the ordinary and bite. 4. Pain: A dog in pain wants to protect what hurts and may lash out to be left alone. 5. Mental Illness: Dogs can deal with mental illness just like humans. OCD, extreme fear, or separation anxiety can get a dog out of sorts.