Hi there and thanks for the post
Sorry for the delay i am trying to get through things that i have missed.
Simon does seem to have a little aggression streak but we will try to get him through this. I think the issues may be based around some dominance aggression.
I think Simon may think he is the boss around the house and so can put people in there place when he is not happy about what is going on.
With all dominance issues he needs to learn he is in fact at the bottom of the pack.
So as always we will start with some alpha training to make sure he knows his place. He will be much happier knowing he is at the bottom of the pack and not having to look after everyone else.
Some ideas to help with this -
1) Simon should be fed last and never from the table
2) When you arrive home wait 10-15 minutes until Simon has calmed down before you give them any attention
3) If Simon is lying in the hallway make him move out of the way. Stepping over or around him only lets them know that they are boss. If he is being aggressive then leaving a lead on him will make it very easy for you to move him safetly.
4) Simon should wait until you have walked through a doorway before they can. You can even practice this by putting them on the lead and walking them around the house!
After a few weeks of a change in the order of place in the house you will start to notice some changes. The next big step is obedience.
The more obedient Simon is the easier he will be able to control no matter what the circumstance or situation.
Take him to a quiet secluded area and practice the basic commands of sit, stay and come for 10-15 minutes twice a day.
Obedience and alpha training can make a huge difference no matter what the problem but will not completely solve the problems. He does need some more direct behavioural modification to fix him and i promise you this will take time.
First things first Simon needs to be reprimanded for any aggressive behaviour whether this be growling, barking, showing his teeth, lunging or biting. You need to reprimand him quickly and properly so that he knows exactly what he has done wrong.
The best way to tell him off is with a loud GRRRRRR or AHHHHHH as well as either throwing a large blanket over him or squirting him with a water pistol. This is a very good approach and does wonders.
You need to be consistent with telling him off no matter how minor or major the degree of aggression.
After he is reprimanded take him away from where he did it to a quiet room or garage. This will also distract him. Leave him there for 15 minutes until he has calmed down and then get him out again. Time out is very helpful.
Often what i find helps in these situations is to completely ignore Simon for an enitre day. This means don't look at him, don't talk to him and don't pet him. This applies to everyone in the house as well as visitors.
This will help SImon realise he is not the top dog and helps gets the ball rolling with these issues.
When it comes to petting him etc try and pet him once then leave him alone and carry on what you are doing. With one pat he won't have the chance to get grumpy at you when he thinks he has had enough.
After a few days of this you can extend it to 2 pats.....carry on like this slowly extending the number of pats he has. This helps reinforce that him getting attention is on your terms not his.
If at any stage he gets aggressive he needs to be told off just like i mentions.
When people come over make sure you tell them what is going on and how they can help. Often visitors can inadvertently undo your good work so make sure you let them know.
If worse comes to worse you can always put him in a kennel outside. Often with a change in environment things can get a lot better.
Also there may be a need at some stage for some medication to reduce his aggression. I find DAP and rescue remedy very good but if these don't help he may need some more serious medication.
Good luck, be patient and remember i am here to help so don't be afraid to ask any more questions you have
Todd