I would like to stress the importance of not relying soley on internet advice with the problem you are having with your dog. We got a dog in March from the animal shelter when it was 2 months old and very quickly she would growl at us when we came near her when she was eating. After about a month she bit me, and at that point I decided we needed professional help.
Unfortunately the help that we got was not suitable for our dog (although we didn't realise it at the time because the trainer managed to solve the problem of food aggression - but as time went on her aggression was expressed through other types of aggressive behaviour).
Her behaviour only became worse, and we brought in another trainer this week, who unfortunately advised us that the best thing we could do was find another home for the dog. Yesterday we rehomed her, and I'm completely devastated. It all started with food aggression that we didn't know how to deal with. It's important to find someone professional who's training philosophy is in line with yours and who relates to all aspects of the dog life and personality. Our dog was found wandering around at the age of 2 months, and we believe she missed out on that crucial period of socialisation. The first trainer didn't relate to that and took a very tough line with her in order to stamp out the aggression. The new trainer we spoke to this week explained to us how important her history was and how we should have dealt with her from the very beginning. We were lucky, we found an excellent home for her, and I'm very grateful that I didn't have to put her to sleep. My advice is don't ignore this problem...and don't deal with it by yourself - find a great trainer to help you.
Good luck
