Secure him to a leash and walk him around the object/space you want him to guard. Do this once in the morning and once in the evening. This will reinforce to him that the item in question falls within his territory. He will then naturally want to defend it.

In the day, you can also tether him on a long leash. Make sure he has enough space to walk around the item/space. This will further make it feel like it falls under his remit.

Try and start this training when he is just a puppy. Dobermans are most receptive when they are still young. So, if you want swift results, start as early as possible.

You will need to encourage any of the signs of aggression you want to see when he’s guarding something. This means handing over a tasty treat when you see him bark at an approaching stranger.

It is important you do not use fear to make him aggressive. Fear could quickly lead to him biting and causing serious damage to another person or pet. Instead, opt for positive reinforcement. Dobermans respond best to this type of training.

Spend a couple of days monitoring him for situations which cause him to bark. You are going to use these triggers to teach him to bark on command. When he is about to eat or go out for walk are likely occasions.

Now start giving a ‘bark’ command in a clear, but firm voice when he is about to bark. Once he then does just that, hand over a tasty treat. You can also give him some verbal praise. Spend several minutes each day doing this.

After several days he will associate the command with barking. You can now start giving the command when he isn’t already in a bark-inducing situation. Continue to give him treats until he responds every time.

Have someone your Doberman does not know approach the item/place you want him to guard. If it’s your house, have the stranger knock on the door. Now use the ‘bark’ instruction to get him barking. Make sure the stranger then shouts/screams and runs away. This is important, it tells him he needs to bark until the person leaves.

Once the stranger has fled, hand over a mouth-watering treat. Practice this every other day but use different people each time. It will soon become habit to bark when someone approaches and you won’t even need to give the instruction.

Sign your Doberman up for obedience classes. The earlier in his life you can do this the better. This will instil discipline as well as teaching him a number of useful commands, from ‘down’ to ‘stay’.

Make sure he gets to spend positive time with other dogs and humans from an early age. You need him to know what behavior is and isn’t normal. Otherwise he may become overly aggressive and unsafe to be around.

Have someone your Doberman does not know knock on your door or windows. Then point at them and get animated. Dogs mirror their owners behavior, so if you show the stranger lots of interest, so will he. Keep encouraging until he gets so worked up that he barks.

As soon as he barks, make sure he gets a decent reward. The better the reward, the more likely he will be to repeat the behavior again. Also, try to give the treat within a few seconds of him barking, otherwise he may not associate the action with the reward.

This training will only yield swift results if you can practice regularly. Aim for every other day, if not, at least a couple a times a week. You should praise and reward him for all signs of loyalty and interest in strangers until it becomes habit.