My 15 month old male German Shepherd has become very aggresive to visitors to my house.  He is fine with my family, but when we have visitors he started about 2 months ago to try to attack them when they enter my house (he nipped my brother in law and my sister).  We now put him in the kitchen when people first come in to the house and let him out after about 5 minutes when they are sitting down.  I then get them to give him titbits and he will then settle down lying on the floor.  When they stand up he jumps up barking and snapping at them.  What more can I do?  Is this something he will grow out of or has he become a dangerous dog?  I don't want to get rid of him as he is really a lovely dog.  We attend training classes 2 or 3 times a week and he is a fantastic worker.  I do not want to come to the point where he actually hurts someone and would like to be able to have freinds and family back visiting again.  What can I do?

Dogs do not "grow out" of this behaviour; in fact the longer they are allowed to practise it the better they become!

I think you really need the services of an experienced accredited behaviourist to visit with you, observe the dog's behaviour in the flesh and who will provide you with a regime of behaviour modification tailor made for your dog in your situation.

Please do NOT go to anyone NOT accredited to either the APBC or the UKRCB; your vet will be able to refer you to a properly qualified individual as opposed to someone who has undergone only 6 weeks of "training" and calls themselves a "behaviourist"

Your dog needs professional attention immediately before he moves on to the next stage, actually biting.

The only reason I questioned whether he might grow out of this behaviour is that experienced German Shepherd people from my local BAGSD club I talk to seem to think that at his age he is going through a teenage boy sort of stage and should calm down.  This is my first shepherd so I've had no personal experience of this.

I've had GSDs for over 40 years & never had one behave like this. My father had one that was always going for people back in the 1950's but she was very nervous & sadly typical of her breeding(6 lines to Avon Prince). She was a fear biter & was PTS after attacking my brother.

I do not think your dog is the same as this bitch, he could be possessive & this is why he dislikes visitors

What you need is some experienced dog people to help you & call round one at a time & put him out of the room with a treat when they arrived & then bring him into the room on a lead(with a muzzle if you are really worried about an avtual attack0 have the visitor totally ignore him & I do mean totally(which is why they must very exeprienced dog people).

They can hold a dish with a treat it but they must just hold the bowl no talking eye contact etc. If he does not react then he can have the treat this will teach him the visitors are a source of reward rather than a threat

Then you can remove him from the room before they go & treat him when leaving him another room.

I do think you need professional help though & I would contact your vet. giving behaviourial advice over the internet is fraught with dangers

An experienced owner may well help a gobby GSD grow out of this sort of behaviour through careful handling, but seeing as this is your first GSD, I would take some advice from an experienced behaviourist as already advised ;)

Thanks for all of your help.  Can anyone recommend a good behaviourist in the Harrow (NW London) area?  I have seen a website called Dog Listener run by Stan Rawlinson and wondered whether he was good.  Also what will I be expected to pay?

Ask your vet for a referral (and at the same time ask the vet to check your dog over physically - there may be a physical problem that is making him more gobby than is normal for an adolescent GSD) You should be referred to a member of the Association of Pet dog Trainers with an interest in behaviour, or a member of the United Kingdom Register of Canine Behaviourists.
Mr Rawlinson has his followers, I am not one of them...........

http://www.apdt.co.uk/index2.htm

Have a look here, the APBC Association of Pet Behaviour Counsellors, will not see anyone without a vet referral but they are accredited, experienced behaviourists with both the necessary academic and empirical knowledge to help you.

whilst he is going through this phase, could you perhaps put him in a crate when visitors come round ? if the crate is in the same room as the visitors he will be able to see that you are happy to accept them into your house and he hopefully wil become acustomed to their presence but be unable to harm them.