Secure him to a leash and then walk around the object or space you want him to protect. If you walk him around the perimeter each morning, he will soon begin to feel that anything within it is his territory and therefore his to defend.

When evening comes, secure him to a leash and walk him around the permitter again. Remain calm and relatively quiet as you go, you want him to concentrate. This will further cement where his territory begins and ends.

The earlier you can start training him to be a guard dog the better. So, take him to obedience training classes from an early age. Great Danes are like sponges to begin with, so they should quickly pick up commands.

Give him verbal praise and treats whenever you see any guard-like behaviour. For example, taking an interest in strangers, barking or being protective should all be encouraged. This will help him naturally develop into a guard dog.

Due to the size of Great Danes, it is important you never punish him. This may only make him aggressive and since he’s so strong he could seriously injure someone. Instead, use positive reinforcement throughout training.

Spend a couple of days monitoring him and looking for situations which naturally cause him to bark. When you are about to feed him or take him out for a walk are likely occasions.

Now put him in one of these situations and give a ‘bark’ command just before or as he barks. You can use any word or phrase you like, Great Danes can learn hundreds of different commands. Also, make sure you give the command in a clear, but firm voice.

As soon as he does bark, hand over a tasty treat and some verbal praise. Make sure he gets the treat within a few seconds of barking, otherwise he may not link the action with the reward. Practice this for 10 minutes each day. After a couple of days you can then start giving the command in a variety of situations.

Now have a friend or neighbor approach your Great Dane when he is standing by the item or space you want him to protect. As soon as they come within 15 feet, instruct him to bark. Then have the intruder shout and run away. This is important--it will teach him he needs to bark until they flee. Then you can hand over a tasty reward.

Over the next week or so, try and practice this at least every other day. Have someone different approach each time and give the ‘bark’ instruction. Do this regularly and it will soon become habit to bark whenever anyone approaches At this point, you can slowly cut out the treats.

To start with, have your Great Dane meet as many people and pets as possible. This will help build his confidence. He won’t be an effective guard dog if he’s shy or nervous around people.

Teach him to ‘sit’, lie ‘down’ and ‘wait’. This discipline will cement your position as pack leader. Also, it will ensure you can control him in tense situations and train him to follow any number of other commands that will be useful when he’s a guard dog.

Tether him to a long leash around the area or object you want him to protect. If he spends each day like this, he will soon begin to think of that space as his territory. He will then naturally want to defend it.

Have people he does not know slowly approach. Then encourage him to take an interest and bark at them. You can do this by waving, pointing and getting animated when they approach. This will get him worked up. Then as soon as he barks, give him a tasty treat. Do this every time and he will soon naturally bark when anyone approaches.

It is important you do not let him bark at family or people that he does know. If he does, quietly remove him from the area and do not give him any rewards or attention. You need him to only bark at strangers.