It is completely natural to be afraid of something that might represent danger. Fear occurs as a result of inner or outer sensation. It is emphasised, unpleasant and it feels like a threat.
Types of fear
1. "Existential fear" – life and safety of a dog are in danger. Escape is the best act because it reduces the possibility of getting hurt. If the escape is impossible, the only option left for salvation as an outcome is to fight – at least as a defence until there is another shot for flight.
2. "Social fear" – it occurs when they get in touch with members of their own species. A dog that runs away prevents any social contact.
Fear intensity
1. Smaller intensity – a dog just steps back, makes few steps to distance itself from danger and move to a place where it feels safer. With some dogs, their neck hair stands up in order to appear bigger and discourage the attacker.
2. Bigger intensity – fear overtakes the brain. It can "run away with tail between its legs". In that case, it will completely shrug, bend its legs, lower its head and ears, and lower its tail or tuck it between its back legs and run. Or it can "petrify". In this case the brain totally blocks and so does the body.
Even the most timid dog might attack with full strength if it feels cornered in last attempt to escape.