[merge] The owners of the property are required by law to indicate a guard dog is on duty on the premises by means of signs at each designated entrance.
Most guard dogs will only defend the perimiter of the property and never go further. Intimidation is their first weapon and they'll bark, snarl, show teeth and/or try to make themselves look bigger to scare away intruders.
In order to successfully negotiate this type of situation, STAY CALM, make yourself appear as small as possible by avoiding rapid movements, keeping your arms on your sides and backing away slowly. Avoiding direct eye contact with the dog is essential as it could be interpreted as a threat or a challenge. Using soothing tones of voice or not speaking at all is encouraged. Phrases such as "good doggy", "I'm going away now" etc. Only turn your back to a guard dog once he has stopped trying to intimidate you, usually once you have left the premises.
DO NOT RUN UNLESS ABSOLUTELY NECESSARY. Running triggers an instinctual chase reaction in dogs and will definitely result in getting injured if you can't outrun the dog. If you must run away, locate the nearest escape, high point or any other place that will make it harder it impossible for the dog to reach you
This will generally only work if you're not caught by surprise, you've identified the presence of the dog and you're still both seperated by a fair distance.
If the guard dog catches you by surprise, do not challenge it by screaming or kicking. Make yourself small, avoid eye contact, and slowly head to the nearest exit.
Dogs are trained to follow the freshest scent and not a scent in particular. You can confuse it by looping and crossing your path. This can give you extra time to escape it.
Dogs will generally not attack unless you trespass their tolerance limit, meaning if you venture too far into their grounds or if you ignore their intimidation tactics.
Police dogs are trained to bring perpetrators down to the ground rather than injure them by dragging or pulling. Injuries can occur but they're not the intention. Guard dogs are difficult to indentify and it's safer not to assume anything. They are usually trained to grab the wrists, arms or calves. Rapid bites can also be used to slow down a perpetrator. Others can be unusually vicious and therefore very dangerous.
If an altercation is inevitable, try to protect you face and throat as they are vital body parts predatorial animals such as dogs will target to bring down an intruder. Rolling into a ball with your knees and elbows together and your face down to the ground will limit risks of severe injuries to vital body parts.
Know that the dog is only doing it's job and if you lead it to believe that you won't fight back and leave, it will hopefully leave you alone.
If you feel you must fight back, remember that they are potent predators and their size can be deceiving of their strength. Aim for the nose, eyes and ribs. Having only one mouth, they can only bite down one hand at a time and that leaves you with one fist and two legs to fight back. Immobilizing by force a dog can show it who is in control and who is stronger. In some cases, this will defeat it and the dog will leave you alone while you leave, but only if you leave.
By all means, avoid resolving to fighting the animal unless it is truly threatening your survival. Try avoiding entirely situations where you could end up in a violent confrontation with an animal.