Basically, my dog up until now has never displayed any aggression other than barking when post comes through the door or when someone comes to the door. Hes always been fine with new people and new dogs and is always friendly. A couple of days ago i got up in the morning and went to take him out and when i went to pat him he snarled his teeth, which i have never seen him do before. i got quite a fright and wasnt sure how to address this? Ever since if i go anywhere near him or even so much as walk past him he growls at me but is still friendly and playful with my boyfriend and other family members. I've also noticed that he has been staring at me basically all the time we are in the same room and i have had to resort to my boyfriend taking him for his walks now as he refuses to let me put his lead on. Also if i fill his food bowl he wont touch it but if someone else picks it up n pretends to put more in it he will be more than happy to run up to it and eat it! Im really worried as to what has caused this sudden change in behaviour. i have never punished him for anything and i am a strong believer in positive reinforcement which is what we enforced when training him. Has anyone experianced this sudden change in behaviour before? He has an appointment to be neutered in two weeks but i know that although this may reduce agression it wont stop problems that already exist. Please Help!