Many people live in terror of being attacked by an aggressive dog, and in some cases this fear is well justified. Any dog can become dangerous if it's raised improperly, and some dog owners aren't equipped with the necessary knowledge required to handle their pets. Depending on the size of the animal involved, a dog attack can easily result in serious injury or even death. When dealing with a vicious dog, you can take action to minimise your risk. In many cases, your natural reaction to fear will actually work against you because it plays into the canine's predatory instincts.
Never approach any dog when the owner isn't present to introduce you to the animal. Dogs use their owner's behaviour to help them make judgments about new people entering their territory. If the dog can't see its owner welcoming you, the animal has fewer reasons to be trustful.
Don't mess with dogs that are eating or chewing on toys. Even friendly dogs can have strong guard instincts related to their food, and they can react in unexpected ways.
If a dog barks, snarls or growls at you, take those warnings seriously. In most cases the creature doesn't actually want to attack you. The intimidating behaviour is meant to frighten you into respecting its territorial boundaries. As long as you take heed of the warning, and give the dog plenty of space, you can usually avoid being bitten.
Regardless of your fear, you must never turn your back to an angry dog and never run away. Remember that dogs are predatory, and giving chase is something they actually enjoy. If you turn around or run, the dog will perceive that as a fearful and weak reaction. This makes dogs more likely to act on their aggression.
Canines perceive eye contact as a challenge to their authority, and it can make the animals more hostile, so never look directly into their eyes, especially if the dog is already showing aggressive behaviour.
Don't make any sudden movements. Dogs can be startled by quick motions and bite suddenly when dealing with new people. Remember that just because a dog seems outwardly calm doesn't necessarily mean that it's feeling that way on the inside.
When approached by a hostile dog, you must hold your ground, and be still until you feel the situation is under control, and then back away from the animal slowly. You are trying to convey a sense of confidence without aggression.
In a worst case scenario, you may want to rely on a dog repellent spray. These are like mace for canines, and they're recommended for people whose lifestyle brings them into frequent contact with aggressive dogs. A good example would be someone with a particularly dangerous walking route.
If everything fails, and the dog attacks you anyway, try to put something such as a purse between you and the animal. If you have nothing else, just use your arm. Try to avoid going to the ground because that is where the dog can do the most damage to you in the shortest amount of time. Once the dog is attacking you, survival is your only concern and you'll have to fight with as much fury as you can summon.