
I have never had a Newfie, but I know what you are going through, Buster has been a handfull but has never showed any agression or food-guarding.
I'm sure you know that if this behaviour isn't stopped it will get worse and worse. It sounds like your boy is very strong-willed, knows he's big and strong and knows he can use his size & weight to his advantage!
I've been through the food-stealing with Buster, all of a sudden one day he pushed ME (I am the one he always listens to!!) out of the way as his head appeared on the work-top and he grabbed a slice of bread, over the next few days he got worse and worse (I'm assuming the fact his fist attempt was succesfull spurred him on!) to the point I had to shut him out of the kitchen if food was being prepared, before this he would lay down paying no attention.
What worked for me re the food-stealing - ensure the dog was never left around food without me present.
I refused to keep him shut out of the kitchen while I was preparing food as to me that seemed like avoidning the issue, so I started giving him his knong with something xtra tasty in while I was busy preparing food. It did mean I had to have eyes in the back of my head as if he thought I wasn't paying attention he would try to steal the food, if that happened he would be shut out of the kitchen for a few mins & then let back in.
When he would reliably occupy himself with the kong while I was preparing food, I then progressed to leaving the kong on the side for a few minutes before giving it to him (he was fucused on waiting for the kong, not the food I was preparing).
I then made him wait longer and longer each day until he nolonger gets a kong, he gets a treat for laying down and ignoring the food I'm preparing, now it's got to the stage that he can't be bothered to wait for a little treat so most of the time he doesn't even bother to come in the kitchen while I'm cooking.
As for stealing off of people in the livingroom - he never gets left with the children if they have food, apart from this if he cant lay down nicely he gets shut in a different room, he soon learnt that it's better for him to control himself. He never gets given food of anybodies plates EVER, if there is some suitable left overs I will put them in his bowl after we've all finished.
>Firstly, he will not let you stroke him on the head as he just 'goes for you', he's just done this at my 8 year old son and caused blood, he was chewing a bone at the time tho'! but he's always like that even if he's not eating or chewing anything
Don't let your children near the dog when he's eating anything (this isn't a method to help fix the problem but it will keep your children safe). Personally I wouldn't let him have a bone if he's guarding, I aslo wouldn't feed a high-protein diet, but this is a desicion you need to make for yourself.
As this seems to be linked with his head being touched I think it wise for you to get him checked by the vet, hearing/eyesight problems need to ruled out (as well as many other potential causes) as these could easily make him feel vulnerable.
After medical issues have been ruled out I think you need a behaviourist, these problems can be sorted out but it's best to get advice from somebody who can see for thierself whats happeing and has the experience to give you the correct advice.
To me it sounds like a stong-willed youngster that needs some consistency, I'm not saying that you are not putting in the effort with his training, but when you have a strong willed, huge dog, you need to find a way to stay confident (they know when you aren't and will take advantage), calm and in control, you aslo need to make sure that you are controlling him with your mind rather than with physical strength - ie, plan-ahead, entice the behaviour you want etc.. rather than result to dragging him by his coller or pushing him down when he jumps up at the table.
The best exapmle I can think of with this is Buster didn't want to come back from a walk the other day - he found a smell he wanted to follow, I gave a little tug on his lead and said 'come' - he planted his feet into the ground and actually started to walk backwards - pulling me with him. My dad was with me and offered to help me pull him away from the smell, I refused and told him that I can't rely on pysical force to control him or he will learn to use his strength agaisnt me, so I got out a piece of cheese and wafted it under his nose - nothing, he didn't care, so I made that piece of cheese do the highland fling infront of his nose and made all sorts of stupid high pithced noised, he relented - the cheese was now far too temping and he gave up his protest and followed me. I made it a battle of wills - my will is much stronger than his so I know I can win that way everytime, he may be a very strong dog, but he is only a dog, therfore i can out-think him :)
Your Newfie is not a lost cause, but it would be a very good idea to get some proffesional help here.